Preheat oven to 300 degrees F. Spread bread pieces in a shallow baking pan. Bake in preheated oven for 10 to 15 minutes or until bread is dry, stirring twice; cool. Transfer to a large mixing bowl; set aside.
In a medium saucepan, cook onion in butter until tender. Stir in poultry seasoning and salt. Add butter mixture to bread and toss to coat. Add enough broth or water to moisten.
Spoon some stuffing into body cavity of turkey. Spoon any remaining stuffing into a baking dish or casserole; cover and chill. Pull neck skin to back and fasten with a skewer. If a band of skin crosses tail, tuck drumsticks under band. If there is no band, tie drumsticks to tail. Twist wing tips under the back, if desired. Place bird, breast side up, on a rack in a shallow roasting pan; brush with cooking oil. Insert a meat thermometer into center of one of the inside thigh muscles. The thermometer should not touch the bone. Cover with foil, leaving air space between bird and foil. Lightly press the foil to the ends of drumsticks and neck to enclose bird.
Roast in a 325 degrees F oven for 3-1/4 to 3-3/4 hours or until thermometer registers 180 degrees F (instant-read thermometer inserted into stuffing should register 165 degrees ). Uncover bird and cut band of skin or string between drumsticks after 2 hours. Uncover stuffing in casserole and add to oven the last 30 minutes of roasting. Remove bird from oven; cover. Let stand 15 minutes before carving. Transfer to a serving platter. If desired, garnish with baby greens. Makes 8 to 10 servings.