As the leaves begin to fall and the wind begins to blow cool and crisp. Our time outside is limited. While outside during your play time. Have a small hunt for fun items. Such as different size of leaves, rocks, grass/weeds and anything else that maybe fascinating to a child's eyes and imagination.
Once you have a small or large collection of items take them inside.
Sort them out into categories. You could start out with sorting by look a likes. ex: leaves with leaves, rocks with rocks etc.
Once sorted place a few leaves under a white piece of construction paper or printer paper. use a crayon or several colors of crayons. Color over the white paper and see the imprint of the leaves on the paper. Since you probably cant place the rocks under the paper unless they are small and flat. place them on top of the paper and have them trace it. then make funny faces inside the shapes.
The children can describe the shapes and sizes of the leaves and rocks and weeds/grass. Also talk about the textures. Smooth, soft, prickly, ruff etc.
Let your child use their imagination. They may even use the rocks and other materials found to making other shapes and rock people.