Leaves can be used as a simple backdrop, or they can be used as prop. One of my favorite ways to shoot with leaves is to have the subject grab a large armful of leaves and throw them up into the air. I then rapidly capture photos as the leaves fall down around them. If you want great candid photos with a group of children or a family, a leaf fight might be just the ticket.
Leaves will always be among my favorite items to photograph. The bright colors make everything pop.