sallyanne got it right! My (wife's) aunt on c/Arrieta in Madrid used to roast a Turkey for Christmas, so I'm sure they're available, even if you have to order them in advance.
I'm old enough to remember the days before frozen Turkeys: the smells of Turkey feathers burning as Mom scorched the bird after we did as much as we could to de-feather the bird. The stuffing was bread (or cornbread) with onions (lots of onions) and sausage meat (much as we make it now). We used the neck and other parts for gravy stock. You should be able to find your vegetables at any GreenGrocer's stand.

You can make Thursday a San Pavo to remember!