Specific for elementary
Teacher's College Reading Writing Project list of mentor text for various units K-6: an invaluable resource even if you don't teach the Units of Study:
The blog, A Year of Reading, suggests mentor text and text sets. This blog, for instance, shows students how to use subtitles and here's a link to TextSets on Instagram. You might also want to check out Franki Sibberson's website.
I'm the Teacher has quite a few mentor texts.
Kate Messner's announcement on Teachers Write Summer 2019 Mentor Text: Along with explaining what Teachers Write is about, she includes several books she uses as mentors.
For the love of mentor texts: Jennifer Sniadecki's very practical and specific suggestions
Writing Fix has a great list of books.
Mrs. Wills Kindergarten blog: Using mentor texts in kindergarten
Ideas for mentor texts for the primary classroom.
Ideas for mentor texts in Spanish
Want a mentor text for persuasive writing? Try One Word from Sophia and when you read this blog, you'll learn about GiftLit.
Ideas for mentor texts for writing personal narrative
Tips for using mentor text and a great list for grades 1 and 2
Ideas from Two Writing Teachers and more from Two Writing Teachers
From Mentor Texts to Mentors in First Grade – Choice Literacy.pdfFrom Mentor Texts to Mentors
Katie DiCesare shares how she uses mentor text with her first graders.
Launching Writing Workshop_ Mentor Texts – Choice Literacy.pdfLaunching the Writing Workshop with Mentors
See what this looks like in a second grade classroom.