Easy Hamburger Dish

3 lb. ground beef
1 medium onion, chopped
1 (16 oz.) can tomatoes
1 (16 oz.) can tomato sauce
1 can green beans, drained
1 small can mushrooms, drained
10 oz. pkg. Longhorn cheese, grated
3 c. instant rice

Prepare rice according to package. Saute ground beef and onion; drain. Place in crock pot. Add tomatoes, tomato sauce, green beans and mushrooms. Cook 4 to 5 hours.
May be served over rice, or rice mixed with hamburger and poured into large baking dish and cheese on top. Heat in oven (350°) until cheese melts.