Americans of all shapes, sizes, colors and ethnic heritages will come together on Thursday to celebrate that most American of Holidays, Thanksgiving. Originally conceived to celebrate the first year the Pilgrims survived in the New World, and coinciding with the final harvest of crops before the onset of winter, Thanksgiving has come to mean a celebration of all things American. The turkey, an all-American bird with the misfortune of having delicious meat, is the centerpiece of most holiday feasts. Accompanying the bird are other American staples of holiday fare; pumpkin pie, mince meat pie, stuffing for the bird (the variety of which is a regional thing), sweet potatoes, green-bean casserole, cranberry sauce and a host of other choices.