Mix tomatoes, onion, jalapeno pepper, cilantro, and garlic together in a bowl; add lime juice and salt and mix well. Refrigerate pico de gallo until flavors blend, at least 4 hours.
Place black-eyed peas in a stockpot and pour in enough water to cover by 1 inch; bring to a boil. Reduce heat to medium-low and simmer until peas are tender, about 1 hour. Stir pico de gallo into peas.