Not quite sure if you are looking for blocks that appear on barns or patterns for barns to put on a quilt. I live in Eastern Tennessee where you see alot of barns with quilt blocks in this area as part of the Appalachian Quilt Trail. The website below is a wonderful reference for block patterns on barns as well as giving you a feel for our lovely area. Please check it out:
http://www.vacationaqt.com/trail/by-pattern/