Preheat oven to 325 degrees F (165 degrees C). Butter one 2 quart casserole dish.
In a saute pan, cook onion and celery in butter until soft.
In a mixing bowl, combine onion and celery, bread cubes, poultry seasonings, mushrooms, egg and stock. Mix well and add to casserole dish. Bake for 1 hour.
