Your child's nature collection, glue, cardboard
Next time you return from a nature walk with a pocketful of rocks and leaves, put them all out on your kitchen table and see if you can create a mosaic from them. Sort them by color or shade and then arrange them into a pattern. You can glue it down for a keepsake or you can keep your nature items in a box to be pulled out for regular use. If you have a good-sized nature collection, you can find a pattern, like a mandala, or an image for your child to mimic in his mosaic. A rock or seashell collection is especially good for this project.