Since it's fall, there are leaves all over our backyard. We went out one day, each with a brown paper bag, and collected different kinds of leaves.
When we came back inside, I made simple books for the boys using white printer paper folded in half, with a piece of construction paper fold in half on top as the cover. I stapled them together on the edge and the boys decorated the covers with crayons. Then they glued their favorite leaves inside!