Heat oven to 400°F. Grease large cookie sheet. In large skillet, combine ground beef, onion and green pepper. Cook over medium heat for 8 to 10 minutes or until beef is thoroughly cooked, stirring frequently. Drain. Stir in tomato sauce, mushrooms, salt, pepper, and oregano; mix well.
Reduce heat; simmer while preparing biscuit dough.
Separate dough into 10 biscuits. On greased cookie sheet, press or roll biscuits to form 14x10-inch rectangle. Spread meat mixture over half of dough. Place cheese slices over meat mixture. Carefully fold dough over cheese slices to form long rectangle. Press edges with fork to seal.
Bake at 400°F. for 15 to 20 minutes or until golden brown.