Preheat oven to 450°F. Remove sausage from casing and cook until browned and crumbled. If using fresh pizza dough, sprinkle hard surface with white flour and roll into square or circle until dough is 1/4-inch thick with crust edges. Once dough is rolled out, sprinkle cornmeal on the back of a baking sheet or pizza paddle and transfer dough (to help the pizza slide on and off the backing sheet or pizza stone). Brush olive oil lightly on crust edges. Spread sauce on pizza crust. Sprinkle cheese evenly. Top with cooked Italian sausage. Add sliced mushrooms. Sprinkle to taste with salt, pepper, garlic powder, and oregano. Bake on oven rack, ungreased baking sheet, or pizza stone for 12–15 minutes or until crust is crispy brown and cheese is melted.