Planting Plants Native to NC provides value to pollinators (like bees, butterflies, flies, dragonflies, native predatory and pollinating wasps, and even midges and beetles), and also to birds and other wildlife.  I have seed a range of native bumblebees, carpenter bees, sweat bees, and solitary bees, as well as Monarch and other butterflies.  Leaving the stems in winter provides places for bees to overwinter.  Those butterflies need native plants on which to lay eggs that develop into the next generation of butterflies. 
Having a wide range of native plants in your garden/yard means that pests are less likely to be around.  I have had no issue with pests and don't have to use use insecticides at all.   Even if you grow vegetables, having locally adapted plants will encourage pest control and attract pollinators to maximize your yield. 

We are located conveniently on the East edge of Chapel Hill for Durham, Hillsborough, Pittsboro, Mebane, Burlington, Orange, Alamance and Chatham counties, and the rest of Research Triangle Park (RTP) including Raleigh, Apex and Cary.