Soak black-eyed peas in cold water for 24-36 hours. Occasionally remove the scum that rises to the top of the water. Rinse halfway through the 24 hours, add more water to the pot, and repeat. Drain peas. (If you don't have time to soak your peas, place them in a pot and bring to a boil. Turn off the heat once it reaches a boil and let the peas stand for 1 hour. Drain and use recipe.)
If you're using bacon, place bacon in a large pot over medium heat until bacon is crisp. Remove all but about 3 tablespoons of bacon drippings, but leave the bacon in the pan. If you are using a ham hock, heat bacon drippings in a pot. Add celery and 1 cup of onions to the pan/pot and sauté until soft (about 4 minutes). Add garlic and cook 2 minutes more.
Place black-eyed peas, chicken stock, cayenne pepper, salt, and pepper into the pan. If you are using a ham hock, place it in the pot with the vegetables. Bring to a boil, and then lower to simmer for about 45 minutes to an hour, or until peas are creamy and tender. Stir occasionally. If the liquid evaporates, add more water.
Meanwhile, cook the rice.
Once the peas are done, remove the ham hock and pull any meat off the bone and place the meat into the collards if you're serving with collards (which I highly suggest). Adjust seasonings and top with scallions. Serve over rice.