Preheat oven to 400 degrees, F.
Thoroughly rinse and scrub chicken under cold water, in sink.
Prepare a 9"x13" baking dish with non-stick coating.
Slice and lightly saute mushrooms (optional).
In large mixing bowl, combine soup, riced, water, and pineapple, and mushrooms, onions. Stir well.
Place 1/3 of rice mixture in baking pan.
Set chicken on top bed of rice mixture, breast side up.
Pour remaining rice mixture over chicken.
Salt and pepper to taste.
Cover with foil and bake 2.5 hours, or until internal temperature is 165 degrees F and/or juices run clear.
Allow to set for 10 minutes before serving.