Take the giblets out of the cavity of the turkey.Take the neck of the turkey and chop into 2-inch pieces.Trim the liver and put it in the refrigerator.
Heat 1 tablespoons vegetable oil in a large saucepan over medium-high heat.
Add the turkey neck pieces, the heart and the gizzard. Sauté for about 10 minutes, or until everything is brown on all sides.Quarter an onion and add along with carrot, chicken broth and enough cold water to cover the giblet mixture by 1 inch.
Bring to a simmer.Skim foam that rises to the surface off the top of the mixture.Add thyme, salt and peppercorns.Reduce heat to low and simmer with saucepan partially covered, about 2 hours.Add the turkey liver and simmer an additional 15 to 20 minutes.Strain mixture and reserve stock if you want to use it for something else (like the gravy).
Otherwise, toss it.Cool the giblets.Pull the meat off the turkey neck with your hands.Chop the neck meat, heart, gizzard and liver and set aside.Chop remaining onion.In a large skillet, melt butter over medium heat. Add onion and celery and cook 10 minutes, stirring occasionally.Place vegetables and butter in a mixing bowl and add bread and parsley.
Drizzle enough stock over the bread mixture until it is just moist. Season with poultry seasoning, salt and pepper to taste.Gently toss in reserved neck meat, heart, gizzard and liver.Use to stuff a turkey, or place in a casserole dish, pour an extra 1/2 cup stock over the top, and bake, covered, in a 350 degree oven for 45 minutes, or until hot.