Aside from bringing home pine cones, sea shells, rocks, sticks, worms, and anything else Burl finds along our walks, we've been gathering leaf skeletons. There are several tutorials online on how to prepare your own, but they involve chemicals and tedious work. I've learned that if you look hard enough you'll be able to find them all on your own, just outside. I find them under hydrangea and camellia bushes during Fall, Winter and early Spring.
I've been tucking these little leaves into gifts and samples and other things that I give away. I think they'd look pretty in a simple frame as well. Happy Hunting!