This was my first attempt at popcorn balls, and they really turned out well. They are sticky to make, you need to spray your hands with cooking spray to keep it from sticking while you are shaping the balls.
1/4 cup butter
1 pkg (10.5 oz) mini-marshmallows (beef by-product, woo hoo!)
1 pkg (3 oz) Jell-o (also beef by-product, woo hoo again!), any flavor
12 cups popped popcorn (I recommend using something close to plain, not too much butter)
Microwave butter and marshmallows in a large bowl for 1 1/2- 2 minutes or until marshmallows are puffed. Stir in jell-o and mix until well blended. Add it to the popcorn; toss to coat. Shape into balls with greased hands. Place on wax paper while they harden.