Check out this cute craft idea from Simple Kids Crafts. Their basic idea is just to make a 3D flower from construction paper...that's good, but you can make it even better by using up all of those scraps of recycled paper that are leftover from other craft projects. You just need a circle of this color and a rectangle of that color and you can have a great green craft that your kids will love.

Make a recycled paper bouquet
Turn your recycled paper scraps into this cool flower arrangement.