In a heavy skillet over medium-low heat, cook ground beef, sausage, onion, and garlic until meat is no longer pink and onion is tender; drain off excess fat.
Meanwhile in crockpot, combine undrained tomatoes, tomato sauce, mushrooms, green pepper, tapioca, bay leaves, oregano, basil, pepper, and salt. Stir in browned drained meat mixture.
Cover and cook on LOW for 10 hours or high heat setting for 5 hours. Remove bay leaves. Serve sauce over hot spaghetti.
Serves 8.