I learned a few years ago that Hoppin’ John is a New Year’s Day tradition, probably more popular in areas of the South. It’s said to symbolize good health and prosperity in the coming year. The black-eyed peas are supposed to represent coins, which tie in with prosperity. And since black-eyed peas are actually beans, they’re good for you (they have lots of fiber and are a good source of potassium, protein, and iron), so that certainly ties in with the “good health” part of the symbolism.