Combine rice, celery, onion, mushrooms and carrots. Add eggs, garlic powder, whole wheat flour and oat bran gradually. Shape and fry in oil in a hot frying pan. It may be necessary to dredge burgers with whole wheat flour if they are soggy. Season after frying with more garlic powder. Extra burgers may be frozen for later use. Serve on whole wheat bun with a slice of melted cheese.