From Wikipedia:
In the Southern United States, the peas are typically cooked with a pork product for flavoring (such as bacon, ham bones, fatback, or hog jowl), diced onion, and served with a hot chili sauce or a pepper-flavored vinegar.
The traditional meal also features collard, turnip, or mustard greens, and ham. The peas, since they swell when cooked, symbolize prosperity; the greens symbolize money; the pork, because pigs root forward when foraging, represents positive motion.[5] Cornbread also often accompanies this meal.
These "good luck" traditions supposedly date back to the Civil War, when Union troops, especially in areas targeted by General William Tecumseh Sherman, typically stripped the countryside of all stored food, crops, and livestock, and destroyed whatever they couldn't carry away. At that time, Northerners considered "field peas" and field corn suitable only for animal fodder, and didn't steal or destroy these humble foods.[6]
