Mix celery, green beans, peas and carrots in a saucepan and cover with water. Bring to a boil, and then lower heat and simmer for 8 minutes. Stirring occasionally. Drain.
Melt the butter in a sauce pan and cook and simmer the onion until clear for about 8 minutes.
Stir in 1/3 cup flour, salt and pepper, celery seed, onion powder, Italian seasoning.
Slowly whisk in the chicken broth and milk, stirring constantly until the mixture begins to thicken and then simmer lightly until thickened.
Remove from heat and mix with the drained cooked vegetables and turkey.
Fill pie crust with the turkey and vegetable mixture.
Carefully top with another pie crust, pinching the sides together. Cut several small slits into the top of the pie crust to allow the pie to vent while cooking.
Bake uncovered in the preheated oven until the pie is golden brown, about 30 minutes. If the top of the pie is browning too quickly, place a sheet of foil over the pie crusts and continue to bake. Cool for about 10 minutes before serving.