I love 'em and use the "leaf" as a teaching tool every year ... I never tire of the color and shape ... they are plentiful where I live and FREE!!!
Oak, maple, ginkgo ... just to name a few!
I am using leaves as subjects myself and with my students!
I encourage you to collect some now for their color but select ones that have interesting shapes and you can adjust the color to fit you mood.
Find an older book (garage sale, library sale, resale shop) with absorbent paper for pages, (modern paper can sometimes be too slick and coated which does not work as well). Have one book dedicated for leaves. Whenever you are out and see an interesting leaf, take it home and place it in the specified book. Store the book under a stack of other books for the weight and pressure needed to PRESS the leaves. I am experimenting with the telephone book that just got replaced with the new, smaller one. The paper seems absorbent enough and IT"S FREE!!!!
When you are stumped for a subject, pull out the leaf book and work with one of the collected beauties. Share them with others and trade with them if they have ones you are missing. When I am done for the session, I place the leaves back in the book for another time.