Place sausage in a skillet over medium-high heat, & cook until evenly brown. Drain, & set to the side.
Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9×13 inch baking dish.
In a large bowl, beat together the eggs, condensed cream of mushroom soup, & milk. Stir in the sausage & mushrooms, & pour into the prepared baking dish. Mix in the frozen potato rounds.
Bake in preheated oven for 45 to 50 minutes. Sprinkle with cheese, & bake an additional 10 minutes, or until cheese is melted.