Wash beans and soak overnight in water.
Next morning, drain water; add 7-Up, tomatoes, bacon, salt, pepper, cover and simmer 1 hour.
Add onion, green pepper, celery, tomato sauce, molasses, sugar, ketchup, mustard, Worcestershire sauce, vinegar, cover, and simmer another hour.
Add mushrooms and turn them into a baking dish. Bake covered in slow oven (250 degrees) for 3 to 4 hours.
Remove cover and bake 1 hour longer. (Mine ended up taking two additional hours.)