We used to call this dressing, and since I no longer cook it inside the turkey that’s actually a better name.
Keep it simple, and start with good bread. I use a couple of dense, whole wheat levain loaves from New Seasons Market. Whatever you get, buy it a few days early, cut the slices into cubes, and let them dry out on the counter. Make a lot, enough to fill a couple of 9X12 inch pan or the equivalent. You want plenty of leftovers.
Cook a finely chopped onion, 4-5 ribs of celery, and a bunch of parsley in butter for about 5 minutes; add rubbed sage to taste, at least a couple of teaspoons, preferably more. In a large mixing bowl combine the bread, cooked vegetables, and enough chicken stock to just moisten everything. Don’t go overboard on liquid; the stuffing in the turkey will absorb juices, and you’ll be basting the other stuff with liquid from the roasting pan. I also like to add coarsely chopped hazelnuts (I still call them filberts) or walnuts for a little crunch.