http://en.wikipedia.org/wiki/Mince_pie
History
The origins of the mince pie begins with the medieval pastry, chewette which was either fried or baked. The "chewette" actually contained liver or chopped meat mixed with boiled eggs and ginger. Dried fruit and sweet ingredients would be added to the chewette's filling for variety. By the 16th century 'mince' or shred pie was considered a Christmas specialty. In the mid-17th century the liver and chopped meat was replaced by suet and meat products were no longer generally used in the 'mince' by the 19th century in both North America and Great Britain though traditional suet pies are still made it is no longer the dominant form.
Folklore and Traditions
Folklore states that mince pies are a favourite food of Father Christmas, and that one or two should be left on a plate at the foot of the chimney (along with a small glass of brandy, sherry or milk, and a carrot for the reindeer) as a thank-you for stockings well-filled.
English tradition demands that the mince meat mixture should only be stirred in a clockwise direction. To stir it anticlockwise is to bring bad luck for the coming year.
Tradition also says that one should make a wish whilst eating one's first mince pie of the festive season, and that mince pies should always be eaten in silence.
Eating at least one mince pie on each of the twelve days of Christmas is thought by some people to bring luck for the coming year.
Mince pies should traditionally have a star on top, to represent the Christmas Star which some believe led the shepherds and Magi to the baby Jesus in Bethlehem.