Sausage Rice Casserole

This dish is the ultimate comfort food for me.  I first had this at elementary school lunch (Back in the day when school lunches were yummy!)  I don't make this dish very often, mostly because I forget about it, but when I remember about it, it is always a hit.  The leftovers are probably even better, in fact, I will usually hide the leftovers so no one else takes it!
This recipe is easily doubled if you have a large family.
Marie

2 cups of cooked rice
1 lb of ground sausage, cooked (can also use sausage links, cut up) drain well
1 small onion, chopped fine
1/2 cup chopped celery
1 can cream of mushroom soup
pepper to taste

Saute onion and celery with 1-2 Tbs butter until celery is soft and onions are translucent.  Combine with rest of ingredients in a 2 quart bowl.  Bake at 325 degrees until bubbly and light brown.