Broccoli-Cheese Rice Casserole

I guess since the Broccoli-Cheese Rice Casserole got rave reviews today I should give you the recipe for it also.

From my Aunt Ann (via my sister Val):
Here's the Broccoli-Cheese Rice Casserole. I don't usually use the exact amounts. If I use more broccoli than the recipe calls for, I increase the other ingredients, of course.
Broccoli-Cheese Rice Casserole
2 - 10 oz. pkgs of frozen broccoli (cook slightly, then drain)
Add:
1 can mushroom soup
4-5 fresh mushrooms, cut up (I just use a couple of cans)
Touch of garlic
1 stick margarine
3/4 cup diced onion
1 lb. Velveeta, cubed
1 cup cooked rice
Mix all and bake at 325 for 45 minutes. (I just put mine in the crockpot for 2-3 hours instead.)

Note: I used a jumbo 320z bag of broccoli, 1 1/2 cups of rice before it was cooked and two cans of mushroom soup. It was delicious. As with sewing patterns I don't follow recipes real well either. More of a wing it as I go type of person.