Broccoli Rice Casserole

This is a really old recipe I had and have not made it in a very long time. Found it going threw my recipes the other day and thought I would make it again. Must say as a side dish it makes a LOT. I did think as we wee eating it if we added diced chicken and made it a main meal it it would have been better. May give it a try next time. Also this is the first time I have used Velveeta cheese other than making the rotel dip in I don't know when.
2 cups cooked rice
1 small box frozen broccoli.... cooked
1 can cream of mushroom soup
1/4 cup onion (we added more)
1/4 cup celery *we also added more)
can of mushrooms or fresh if you want to
one small box Velveeta cheese cubed about 2 cups
saute onion and celery in butter or olive oil till clear
mix all ingredients together and place in a buttered baking dish and cook at 350 for about 30 minutes.