The yarn is what makes these snowballs so convincing. I used Pipsqueak™ by Bernat® in Whitey White (naturally). It's a bulky polyester yarn that has a fuzzy, super-soft texture. If you can't find it, try another novelty yarn. Making these snowballs requires absolutely no craft skills. Just tape the end of the yarn to a foam ball and wrap until the ball is completely covered. When you're finished, cut the yarn and weave the tail end under previous layers to secure it.
Make a bunch of yarn snowballs and pile them in a basket or bowl for a wintry centerpiece. You can use your yarn snowballs as decorations around the house or to stage an indoor snowball fight (just kidding--sort of).