May Day is barely celebrated in the United States, but it does have as rich and checkered a history as just about any other eldritch holiday. While many of the countries that celebrate May Day use it as their Labor Day, it has roots going beyond unionists, communists and anarchists to pagans, Celts, and Romans.
If you'd like to do a little celebration for May Day without erecting a telephone pole in your yard or marching your cattle through the fire, you can make easy May baskets and hang them on your neighbors' doorknobs. Don't get caught though, or you might get kissed! You can also make wishing wells or cow puppets for further entertainment.
For more about the ancient customs associated with May Day, a good place to start is Sir James Frazer's classic, The Golden Bough. If you're intimidated by the size or style—it's taking me years to get through—Bartleby.com has a hyperlinked index to help you zip right to the pertinent sections. If you're interested in the political origins of May Day as Labor Day, check out a book on the Haymarket Square Riot.
Maypole graphic courtesy of Warriner Partnership Schools.