Bring the rice and 3-1/2 cups of broth to a boil in a saucepan. For about 20 minutes, reduce heat, cover, and cook the meat until soft.

In the meantime, sauté onion and celery in butter in a skillet until they are soft. Add the remaining 1/2 cup of stock, along with the rice, mushrooms, parsley, poultry seasoning, salt, and pepper. Put into a 13x9-inch baking dish that has been buttered. Bake for 30 minutes at 350 degrees, uncovered. If prefered, garnish with thyme and sage.