For the corn bread, preheat oven to 425°F.
Lightly butter an 8" square baking pan.
In a mixing bowl, stir together flour, cornmeal, baking powder and salt.
In a small bowl, whisk together milk, egg and butter and stir into cornmeal mixture until just combined. Pour into prepared pan and bake on the middle rack for 20-25 minutes, or until corn bread tests done. Cool in pan 5 minutes, then invert onto rack and cool completely. This can be done two days ahead. Keep cornbread well wrapped. Reduce oven to 325°F.
Into a shallow baking pan, crumble cornbread into coarse pieces. Bake 30 minutes, or until it is dry and golden. Set aside to cool completely.
In a large frying pan, heat butter over medium heat. Add onions, celery and mushrooms and cook, stirring often, until vegetables are soft, about 5-7 minutes. Stir in green onion, parsley, thyme, sage, salt and pepper and pecans. Fold onion mixture into cooled dried cornbread. Add lightly beaten egg and enough stock to pull stuffing together. It should be soft enough to be moist but not so runny as to create a mess when stuffing the turkey. Cool stuffing completely before using to stuff a 12 - 14 lb. turkey.