Boil rice and rice water in small saucepan. Cover; cook over low 40 to 45 minutes until tender. Rest covered off heat 10 minutes.
Heat oil in soup pot over medium; cook onion 5 minutes, then garlic 1 minute.
Add peas, broth, bay, and cayenne; simmer partly covered 45 to 55 minutes until peas nearly tender.
Add collards and ham; simmer 15 to 20 minutes until greens and peas tender and ham 165°F.
Discard bay; fold in rice. Simmer 2 minutes; add vinegar and taste before adding up to measured salt.
Divide among six bowls with peas, greens, rice, and ham in each.