Combine the black beans, black-eyed peas, pinto beans, corn, celery, cilantro, red and yellow bell peppers, green onion, pimento peppers, jalapeno pepper and garlic in a large bowl. Set aside.
Bring the rice vinegar, olive oil, sugar, salt and black pepper to a boil in a medium saucepan over medium-high heat until the sugar is dissolved (about 5 minutes). Allow to cool to room temperature and then pour over the bean mixture. Cover and refrigerate anywhere from 2 hours to overnight. Drain before serving.