As a reminder of the day, and possibly inspired by the story of the Indiana Jones packet with its fake stamps, John King Tarpinian pointed me to the Wikipedia entry on J.R.R. Tolkien’s Father Christmas letters:
The letters themselves were written over a period of over 20 years to entertain Tolkien’s children each Christmas. Starting in 1920 when Tolkien’s oldest son was aged three, each Christmas Tolkien would write a letter from Father Christmas about his travels and adventures. Each letter was delivered in an envelope, including North Pole stamps and postage marks as designed by Tolkien.
And the characters and doings in the letters have been said to prefigure elements of Tolkien’s Middle-Earth adventures.