Cheesy Sausage Zucchini Casserole

¾ cup uncooked white rice
1½ c water
1 pound pork sausage
¼ c chopped onion
1 c diced fresh tomato
4 c cubed zucchini
1 (4 ounce) can sliced mushrooms, drained
1 (8 oz) package of shredded cheese
salt and pepper to taste
Combine the rice and water in a small saucepan, and bring to a boil. Reduce heat to low and simmer for about 20 min. until tender. Remove from heat and set aside.
Preheat oven to 325.
Cook sausage and onion in a large skillet over med heat, stirring until evenly browned. Drain excess grease. Stir in zucchini and tomatoes, and cook until tender. Stir in rice, mushrooms, and half of cheese. Season with oregano, salt, and pepper. Spread in 9x13 inch baking dish.
Bake uncovered until cheese is bubbly, about 20 min.