Nature's free art supplies make for amazing masterworks.
Go for a walk with your child around the block, bringing along a grocery bag. Your kid can be in charge of choosing some free souvenirs from the walk, which you will put into the bag. These items include leaves, sticks, stones, seed pods, blades of grass, and so forth. Bougainvillea leaves can be especially nice. The only guidelines here are: don't take too much of any one thing, and don't take anything that belongs to somebody else! (A neighbor's mail, for example, is not available for this project.)
Back at home, take out some glue and construction paper. Help your little one glue the souvenirs to the paper.
Voila! It's a masterpiece! Your child is an artist. And it's fun for everyone. (Except possibly for the neighbor, if your child disregarded one of the above guidelines!)