I had the same peanut butter craving about a month ago. I NEEDED peanut butter, and even went out specifically to buy some. I don't know what I could've been missing, either, but there are worse things to crave for!

When I was a full-on vegetarian about 10 years ago, at the 6 month mark, I had this overwhelming obsession with tuna salad sandwich. I don't even like tuna but I kept on thinking it and even dreaming it. After about a week I figured I must be missing mercury or some other heavy metal in my diet so I gave into the craving and fell off the veggie wagon. Now I'm just a flexitarian.