FREE COLD FOAM: Cold Foam Days at Starbucks take place from May 7 through May 11. Rewards members in the U.S. or Canada can add cold foam to a cold beverage for free.

Starbucks is offering Starbucks Rewards members free cold foam in the U.S and Canada May 7-11. Here's how to redeem the offer.

Starbucks cold foam or its delicious sweet cream -- which should you choose? Well, it depends on what you're looking for as the two are quite different.