Cook manicotti; drain. Mix onion, spinach, bouillon, garlic, thyme, Ricotta, eggs, Parmesan cheese, oregano and half the mushrooms. Fill manicotti shells with spinach mixture. Arrange in greased 9x13 baking dish. Pour tomato sauce and remaining mushrooms over manicotti. Sprinkle with oregano; cover with Mozzarella. Cover and cook at 350 degrees until hot and bubbly, about 25 minutes. ALTERNATE FILLING Brown meat in skillet; drain. Mix with all other ingredients. Stuff manicotti with meat mixture. Proceed as in first recipe.