Stuffed Pasta Shells

1 package (16 ounces) ricotta cheese
1/2 cup shredded mozzarella cheese
1 package frozen chopped spinach, thawed
1/2 cup mushrooms, chopped
1 tablespoon Italian seasonings
Salt and pepper, to taste
1 package large pasta shells
Tomato sauce

Mix together the first 6 ingredients.
Cook a package of large pasta shells until cooked but still firm. Drain the pasta, and rinse with cold water.
Stuff the shells with the filling mixture and arrange them in greased dish.
Cover with canned tomato sauce and bake at 350 degrees for 15-20 minutes.
The filling above can also be used in lasagna.