Preheat oven to 375°F. Heat large nonstick skillet over medium heat until hot. Add Ground Beef and mushrooms; cook 8 to 10 minutes, breaking into 3/4-inch crumbles and stirring occasionally. Remove drippings. Stir in rice, contents of seasoning packet and tomatoes.
Spoon beef mixture into 2-quart baking dish. Stir in water amount indicated in rice package directions, plus 1/2 cup additional water. Cover with aluminum foil.
Bake in 375°F oven 45 to 50 minutes or until water is absorbed. Uncover; sprinkle with cheese. Continue baking, uncovered, 5 minutes or until cheese is melted.
Nutrition information per serving: 379 Calories; 99 kcal Calories from fat; 11 g Total Fat; 5 g Saturated Fat; 3 g Monounsaturated Fat; 86 mg Cholesterol; 822 mg Sodium; 36 g Total Carbohydrate; 2.1 g Dietary Fiber; 35 g Protein; 4.9 mg Iron; 8.1 mg Niacin; 0.4 mg Vitamin B6; 2.3 mcg Vitamin B12; 6.4 mg Zinc; 26.7 mcg Selenium;