Place bread in a single layer on 2 baking sheets. Bake at 250° for 1 hour or until dry. Set aside.
Remove casings from sausage. Cook the sausage in a large nonstick skillet coated with cooking spray over medium heat until browned, stirring to crumble. Place sausage in a large bowl.
Heat oil in pan over medium heat. Add the onion, celery, and mushrooms; cover and cook 10 minutes or until vegetables are tender, stirring occasionally. Remove from heat; stir in thyme and the next 4 ingredients (thyme through pepper). Add the onion mixture, bread, and parsley to sausage; toss gently to combine. Add Homemade Turkey Stock, and stir until moist.
Increase oven temperature to 350°.
Spoon the bread mixture into a 13 x 9-inch baking dish coated with cooking spray. Cover and bake at 350° for 15 minutes. Uncover and bake an additional 20 minutes or until top is crusty.