Stir in broth, collard greens, ham, salt, tomatoes, and bay leaves. Cover and cook on HIGH for about 4 hours or on LOW for about 7-8 hours, or until the peas and vegetables are tender. Discard bay leaves. Taste and season with salt and pepper, if necessary. Ladle into bowls and serve. Garnish with chopped fresh herbs, crushed red pepper flakes, hot sauce, a squeeze of fresh lemon juice, or a splash of apple cider vinegar.