Chicken and Rice Casserole

3 cups diced cooked chicken ( Buy one already cooked at Grocery store)
1 medium onions, diced & sauteed
1 (8 ounce) cans water chestnuts, drained & chopped
2 (14 ounce) cans French style green beans, rinsed & drained
1 (4 ounce) cans pimientos, rinsed & drained
1 (10 ounce) cans condensed cream of celery soup
1 cup mayonnaise
1 (6 ounce) boxes uncle ben's long grain and wild rice blend, cooked according to package directions

1 cup of grated sharp cheddar cheese

1. Preheat oven to 300 degrees. 
2. Mix all ingredients together & pour into a 3-quart casserole.
3. Bake for 25 minutes.