Book Displays: May Day ~ Celebrate Spring!

from Encyclopædia Britannica
May Day, in medieval and modern Europe, holiday (May 1) for the celebration of the return of spring. The observance probably originated in ancient agricultural rituals, and the Greeks and Romans held such festivals. Although later practices varied widely, the celebrations came to include the gathering of wildflowers and green branches, the weaving of floral garlands, the crowning of a May king and queen, and the setting up of a decorated May tree, or Maypole, around which people danced.

By Deborah Byrd in Astronomy Essentials
May Day – an ancient spring festival in the Northern Hemisphere – is an astronomical holiday. It’s one of the year’s four cross-quarter days, or a day that falls more or less midway between an equinox and solstice, in this case the March equinox and June solstice.
May Day also stems from the Celtic festival of Beltane, which was related to the waxing power of the sun as we in the Northern Hemisphere move closer to summer. At Beltane, people lit fires through which livestock were driven and around which people danced, moving in the same direction that the sun crosses the sky.
Wrapping a Maypole with colorful ribbons is perhaps the best known of all May Day traditions. In the Middle Ages, English villages all had Maypoles, which were actual trees brought in from the woods in the midst of rejoicing and raucous merrymaking.

NPR History Department
The curious custom — still practiced in discrete pockets of the country — went something like this: As the month of April rolled to an end, people would begin gathering flowers and candies and other goodies to put in May baskets to hang on the doors of friends, neighbors and loved ones on May 1. Perhaps considered quaint now, in decades past May Basket Day — like the ancient act of dancing around the maypole — was a widespread rite of spring in the United States.