1. Leaf Mazes
This is one of the best leaf activities I have ever come across. It's innovative and simple. Use the fallen leaves to make a maze for kids to play in. With corners and spiral ones. Check them out here.
2. Stapling Fun
Collect colorful leaves. lay them out in a design of your choice. Make sure parts of the neighboring leaves are overlapping each other. Once your design is complete, staple neighboring leaves together. Put it up on your wall. Make sure the kids are careful while using the stapler.
3. Leaf Beating
This activity gives amazingly beautiful results. Collect leaves which are not dry. Lay them out some white cotton cloth. Cover it with tissue. Use a hammer to beat on the leaves. As the pigment leaves the leaf, it bleeds on to the cloth leaving behind beautiful designs. This Japanese art form is called Hapa Zome.