An excellent paper craft site that I've found is called Free-kid-Crafts. It's designed for preschoolers and early school age children.
I've included a few samples from their site below:
|">||Hand Print Peacock
If you look closely at the tail you'll see that it's made with lots of small hand prints. How cool is that?
I had never heard of making leaf creatures until I visited this site. The website has designs for other leaf creatures too, and encourages children to make up some of their own with what ever they find outside.
|Toilet Paper Roll Frog
A very simple and solid paper frog with full assembly instructions.