I found this craft in the Family Fun magazine and loved it because even a 2-year old can do a lot of the crafting herself.
Start with wax paper. Cut pieces of yarn (about one foot each) and dip them in a homemade cornstarch paste (1/4 cup cornstarch and 1/2 cup water heated on stove until thick, mixing constantly).
You scrape off the excess paste, then place the yarn pieces in a heart-shaped cookie cutter. You put in as many as you want, until it is all filled up to your liking.
Then, with clean hands, you press the yarn down and remove the cutter. Repeat to make as many hearts as you want.
Let dry for 24 hours, then use them to decorate however you want.
We strung ours through ribbon and made a heart garland. I love the way they turned out. Let me know if you try it yourself!