1. Sort through and rinse beans several times in cool water.
2. Add to the slow cooker along with the diced carrots, celery, onions, garlic, bay leaf and dried herbs.
3. Add the water. (Use less for a thicker stew, more for more of a soup.)
4. Cover and cook on high for 3 hours, or low for 6 hours.
5. Remove lid from slow cooker and add the salt and pepper, and diced tomatoes.
6. Let cook for another 1-1 ½ hours, or until beans are very soft. (If they are already soft after the initial cooking time, different kinds of beans may vary in cooking time, then add the tomatoes and greens and serve immediately.)
7. Before serving, stir in the chopped greens.
8. Serve over hot cooked brown rice (optional).