Bring brown rice and rice water to a boil in a small saucepan. Cover, reduce heat to low and cook for 40 to 45 minutes until tender, then rest off heat, covered, for 10 minutes.
Heat oil in a soup pot over medium heat. Cook onion for 5 minutes, then add garlic for 1 minute.
Add black-eyed peas, broth, bay leaf and cayenne. Bring to a simmer, partly cover and cook for 45 to 55 minutes until the peas are nearly tender.
Stir in collards and ham and simmer for 15 to 20 minutes until the greens and peas are tender and the ham reaches 165°F.
Discard bay leaf and fold in the cooked brown rice. Simmer for 2 minutes, then stir in vinegar and taste before adding up to the measured salt.
Divide among six bowls, keeping peas, greens, rice and ham in each serving.