Here are some good* mail order sources for various types of fruit and nut plants:
*Sources with poorer ratings are listed separately towards the bottom of the page.
39th Parallel Nursery and Orchard - apple and pear trees, scions, and rootstock - no G.WD rating yet - https://39thparallel.com/
Adams County Nursery - various fruit tree types - excellent G.WD. rating - http://www.acnursery.com/
Bay Laurel Nursery - multiple types of fruit and nut trees and plants - very good G.WD. rating - http://www.baylaurelnursery.com/
Ben's Subtropical Fruiting Plants / Ben Poirier - many rare and subtropical fruit plants - no review (caveat emptor) - http://encantofarms.com/poirier.html
Big Horse Creek Farm - apple trees - excellent G.WD. rating - http://www.bighorsecreekfarm.com/
Blossom Nursery - pawpaw trees & seeds - limited, excellent G.WD. rating - http://www.blossomnursery.com/
Bob Wells Nursery - multiple fruit and nut trees and plants - very good G.WD. rating - http://bobwellsnursery.com/
Boyer Nurseries & Orchards, Inc. - multiple types of fruit trees and plants and nut trees - excellent G.WD. rating - http://www.boyernurseries.com/
Burnt Ridge Nursery - various types of fruit - fairly good G.WD. rating - http://www.burntridgenursery.com/
Century Farm Orchards - apple and pear trees - excellent G.WD. rating, knowledgeable and helpful owner - http://www.centuryfarmorchards.com/
Cloud Mountain Farm - various types of fruit & impressive selection of other plants - excellent G.WD. rating - http://www.cloudmountainfarm.com/
Cummins Nursery - various fruit trees types - excellent G.WD. rating - http://www.cumminsnursery.com/
DeGrandchamp Farm - blueberries - limited, excellent G.WD. rating - http://www.degrandchamps.com/
Double A Vineyards - blueberries - excellent G.WD. rating - https://doubleavineyards.com/
Edible Landscaping -multiple types of fruit - fairly good G.WD. rating - http://www.ediblelandscaping.com/
England's Orchard & Nursery - nut, persimmon, pawpaw, jujube, and asian pear trees - very good G.WD. rating - http://www.nuttrees.net/
Fedco Trees - various types of fruit - excellent G.WD. rating - http://fedcoseeds.com/trees.htm
Finch Blueberries - blueberries - very good G.WD. rating - https://www.finchblueberrynursery.com/
Forestfarm - huge selection of plants - excellent G.WD. rating - http://www.forestfarm.com/
Fruitwood Nursery - multiple types of fruit and nut trees and plants - limited, excellent G.WD. rating - https://fruitwoodnursery.com
Gardens Under Sunlight - many exotic and hard to find fruit - no ratings found - https://www.hardtofindtrees.com/
Going Bananas - banana plants and corms - excellent G.WD. rating - http://www.going-bananas.com/
Grandpa's Orchard, LLC - affiliated with Moser Fruit Tree Sales, Inc. - rootstocks and various types of fruit trees and plants - very good G.WD. rating - http://www.grandpasorchard.com/
Greenmantle Nursery - various types of fruit - very good G.WD. rating - http://www.greenmantlenursery.com/
Grover's Blueberries - blueberries and other berry plants - fairly good G.WD. rating - http://www.groversblueberries.com/
Hartmann's Plant Company - various types of fruit (mostly berries) - excellent G.WD. rating - http://hartmannsplantcompany.com/
Henry Leuthardt Nurseries, Inc. - various types of fruit (specialize in espalier) - limited, marginally good G.WD. rating - http://www.henryleuthardtnurseries.com/
Hidden Springs Nursery - multiple types of organically-grown fruit trees and plants - excellent G.WD. rating - http://www.hiddenspringsnursery.com/
Indiana Berry & Plant Co. - multiple types of small fruit and berries - excellent G.WD. rating - https://indianaberry.com/
Ison's Nursery & Vineyards - multiple types of fruit trees and plants (specialize in muscadines, blueberries and blackberries) - marginal G.WD. rating - http://www.isons.com/
Johnson Nursery, Inc. - multiple types of fruit - excellent G.WD. rating - http://www.johnsonnursery.com/
Jung Quality Garden Seeds - multiple types of fruit trees and plants - marginal G.WD. rating - http://www.jungseed.com/
Just Fruits and Exotics - multiple types of fruit trees and plants - excellent G.WD. rating - http://www.justfruitsandexotics.com/
Maple Valley Orchards - apple, pear, and plum trees, scions, and rootstocks - excellent G.WD. ratings - https://maplevalleyorchards.com/
Montoso Gardens - tropical fruits and seeds - excellent G.WD. rating - http://www.montosogardens.com/
Moser Fruit Tree Sales, Inc. - affiliated with Grandpa's Orchard LLC - rootstocks and fruit trees for commercial growers - limited, excellent G.WD. rating - http://www.forfruittrees.com/
Mountain Gentry - chestnut trees - no G.WD rating yet - https://mountaingentry.com
Nash Nurseries - pawpaw, hybrid chestnut, pine nut, etc. - limited, excellent G.WD. rating - http://www.nashnurseries.com/ - phone: 517-651-5278
Norm's Farms - elderberry cuttings and products - no rating (caveat emptor) - http://normsfarms.com/
Nourse Farms Inc. - berries and small fruit - excellent G.WD. rating - http://www.noursefarms.com/
One Green World (Northwoods Nursery) - multiple types of fruit trees and plants - marginally good G.WD. rating - http://www.onegreenworld.com/
Ort Family Farm - multiple types of fruit trees and plants - 5-star Google rating - https://www.ortfamilyfarm.com/
Peaceful Valley Farm Supply - various types of fruit trees and plants - fairly good G.WD. rating - http://www.groworganic.com/
Pense Nursery - affiliated with Arkansas Berry & Plant Farm, Black Diamond Nursery, Boston Mountain Nurseries, and Bramble Berry Farm - multiple types of berries and grapes - fairly good G.WD. rating - https://penseberryfarm.com/
Planting Justice - multiple types of fruit and nut trees and plants (impressive selection) - excellent G.WD. rating - https://plantingjustice.org/
Raintree Nursery - multiple types of fruit trees and plants - fairly good G.WD. rating - http://www.raintreenursery.com/
Route 9 Cooperative - chestnut trees and seeds - no G.WD. rating yet - https://route9cooperative.com/
Sakuma Bros. Farms - berry plants - 5-star Google rating - https://www.sakumabros.com/
Simmons Plant Farm - blueberries, various berries, grapes, etc - excellent G.WD. rating - http://www.simmonsplantfarm.com/
St. Lawrence Nurseries - various northern climate fruit and nut trees - very good G.WD. rating - https://www.slngrow.com/
Stark Brothers Nurseries & Orchards Company - various fruit trees and plants - marginal G.WD. rating - http://www.starkbros.com/
Trees of Antiquity (formerly Sonoma Antique Apple Nursery) - multiple types of fruit trees and plants - excellent G.WD. rating - http://www.treesofantiquity.com/
Tripple Brook Farm - unusual fruits - good G.WD. rating - http://www.tripplebrookfarm.com/
Van Well Nursery - various fruit and nut trees - excellent G.WD. rating - http://www.vanwell.net/
Vintage Virginia Apples - apple, pear, and quince trees - limited, very good G.WD. rating - https://www.albemarleciderworks.com/
Whitman Farms - small-fruit plants and trees and nut trees - excellent G.WD. rating - http://whitmanfarms.com/
Womack Nursery Co. - multiple fruit and nut trees and plants - very good G.WD rating - http://www.womacknursery.com/
Woodlanders, Inc. - wide variety of hard-to-find southern plants - fairly good G.WD. rating - http://www.woodlanders.net/
Z's Nutty Ridge Nursery - chestnut and hazelnut trees - 5-star Google rating - https://znutty.com/
Here are some mail order sources with poorer reviews for various types of fruit plants:
Aaron's Bulb Farm, Arron's Fruit Nursery, Aaron's Nursery, etc. - see TyTy Nursery
Apple Tree Nursery, Fig Tree Nursery, Pecan Tree Nursery, etc. - see TyTy Nursery
Burgess Seed - see Gurney's Seed & Nursery
DiMeo Farms (DiMeo Blueberry Farms) - blueberries - poor G.WD. rating / scam alert! - http://www.dimeofarms.com/
Direct Gardening - see Gurney's Seed & Nursery
Gurney's Seed & Nursery - multiple types of fruit and nut trees and plants - poor G.WD. rating - http://gurneys.com/
Henry Field's Seed & Nursery - see Gurney's Seed & Nursery
House of Wesley - see Burgess Seed
Inter-State Nurseries - see Burgess Seed
Kelly Nurseries - see Burgess Seed
Morse Nursery - various types of fruit - limited, poor G.WD. rating - http://www.morsenursery.com/
Rhora's Nursery - various nut and fruit trees and plants - limited, poor G.WD. rating - http://www.nuttrees.com/
Spring Hill Nurseries - affiliated with Gardens Alive! - multiple types of plants - poor G.WD. rating - http://springhillnursery.com/
TyTy Nursery - extremely poor reviews / scam alert!
Willis Orchard Company - multiple types of fruit and nut trees and plants - poor G.WD. rating / scam alert! - http://www.willisorchards.com/
Woodstock Nursery - multiple fruit and nut trees and plants, also has selection of crabapples - poor G.WD. rating - http://www.wallace-woodstock.com/