This is an idea that I got from my sister.
All you need is:
3 sheets of orange felt
1 sheet of black felt
Simply cut out three round pieces for the pumpkins and various shapes to make a face. Felt's great because it doesn't tear or wrinkle like paper.
We've enjoyed this activity many times. The other day after making our jack-o-lantern faces the shapes got assembled all over the pumpkins and the next thing you know we're making pizzas. With a little imagination the fun can be endless.