I've always liked Boxing Day (December 26), because it exemplifies how the New World has adapted a tradition from the Old. In England, householders mark Boxing Day by giving small boxed presents to the people who have served them through the year: originally to their household servants (back from the days when households had live-in servants) and then to the dustman, mail carrier, and so on.
We've adapted that tradition in the United States, with our own mercantile twist: on Boxing Day we do not give boxed presents to our servants (for most of us have none); rather, we box up our unliked Christmas presents and take them back to the mall to exchange for something that we do like. Or, in verse:
On Yule, the English eat and drink their fill,
Next morn, they give to those who do their will.
They think our Stateside customs rather strange,
One day we give; the next we all exchange.