In a large skillet over medium-high heat, brown the sausage. If desired, drain fat.
Add onions and mushrooms and cook until tender, set aside in a separate bowl.
In the same skillet, add the oil and hash browns over medium-high heat and cook until golden brown on 1 side. Once golden brown add eggs, add the sausage and mushroom mixture. Scramble together until desired consistency and top with cheese.