May 1st, often called May Day, just might have more holidays than any other day of the year. It's a celebration of Spring. It's a day of political protests. It's a neopagan festival, a saint's feast day, and a day for organized labor. In many countries, it is a national holiday. In medieval England, people would celebrate the start of spring by going out to the country or woods—"going a-maying"—and gathering greenery and flowers, or "bringing in the may."
Another English tradition is the maypole. Some towns had permanent maypoles that would stay up all year; others put up a new one each May. In any event, the pole would be hung with greenery and ribbons, brightly painted, and otherwise decorated, and served as a central point for the festivities.
One of the most popularly known May Day traditions is to hang a basket full of spring flowers on a neighbor's doorknob. The trick is you don't want the neighbor to see you. What a nice surprise when they opened the door. This was a tradition that I always did growing up.