I have a little game that I like to play when I'm bored called "how can I make a ______" then I brainstorm all the possible ways to make something using stuff I already have. 9 times out of 10 I never get around to making the things I dream up, but that's not the point. It's more to entertain myself than anything else.
With that said here's a little sampling of a dialogue I had the other day when folding laundry called "how can I make a pumpkin"
Take a brown paper bag and paint it orange, fill it with scrap paper and twist the top shut. Either paint the twisted handle green or glue green paper around the stem.
Take a paper plate and color (or paint) it orange, staple a piece of green paper and curled green gift ribbon to the top. To make it more fun paint with something unusual like a sponge or cotton balls.
Take an old orange sock, fill it with cotton balls or fabric scraps cut the top off (so it doesn't get to long) and tie it shut with green string. If you're feeling adventurous paint the top with green acrylic paint. Or Sew the top shut with needle and thread.
Cut two pieces of orange construction paper into a large circle. Staple the two pieces together around the edge, leaving the top open wide enough to stuff. Stuff it with scrap paper and staple shut. Add green paper for the stem
Find something cylindrical that would make a good stamp, a round block, soup can, or a lid of some kind. Dip the circular end in orange paint to make your pumpkin. Do it several times and you have a pumpkin patch.
Make ice pumpkins by filling balloons with orange liquid (water with food coloring, or orange drink) and freezing. When liquid is frozen clip the balloon with scissors and it'll come right off.
How's that for a 10 minute brainstorm?