Find a paper napkin with fall leaves or other fall motifs and decoupage them onto the stones. It is so easy and the result looks great. Light colored stones are perfect for this project, but you can also paint darker stones white if you like.
Little fall leaves sewn from wool or felt. These are actually coasters, but gives me an idea to make them in miniature and turn my tiny kitchen "Christmas" tree into a autumn tree with lights and tiny wool leaves for fall.