Southern Shrimp Casserole

From a church cookbook that I've had for years. This has been adjusted to my family's tastes, but everyone I've served it to seems to like it, so I thought I'd share.

• Ready In: 1 hr
• Serves: 6-8

Ingredients

• 1  cup celery, coarsely chopped
• 1⁄2 cup green bell pepper, finely chopped
• 1  cup onion, coarsely chopped
• 1⁄2 cup butter
• 1  cup  condensed tomato soup
• 1  cup rice, cooked
• 1  cup cheddar cheese, shredded
• 1  lb  cooked shrimp (tail off, peeled)
• 1⁄2 teaspoon red pepper flakes
• 1  cup fresh mushrooms, sliced

Directions

1. Saute celery, bell pepper and onion in butter.
2. Slowly add remaining ingredients and stir well.
3. Pour mixture into a 9 X 13 inch casserole dish and bake at 350 degrees for 30 minutes.
4. I top ours with another little sprinkle of cheese before serving.