Our redbuds are covered with
seed pods that resemble bean pods and that's good enough for me, to say nitrogen fixer. I have a few that are over 25 years old and still kicking. In zone 7, they want afternoon shade, but in zone 5 they may be tolerant of more sun. Naturally they are on the edge which I love and the few that I've given more space to get fairly big - much larger than my apples trees.