I'm sure the wee little folk are whopping it up, and for certain, they're wearing green. You've undoubtedly heard about leprechauns, but here's a bit about the origin of the leprechaun legend (from Holiday Symbols and Customs [R 394.26 HOL]:
The legendary creatures known in Ireland as leprechauns were part of a group of fairies known as Luchorpan, which means "the wee ones." Over the years, the name luchorpan became confused with an Irish word meaning, "one-shoemaker." Since shoemakers had a reputation for living alone and having a grumpy nature, the leprechaun was depicted as a solitary creature, usually working on a single shoe rather than a pair. He was a wizened, bearded dwarf who wore a green suit and cap and worked day and night mending the shoes of the other fairies.
I love leprechaun stories, and after a few of these, you'll love them, too:
Bunting, Eve. That's What Leprechaun's Do. [JP BUN]
Calhoun, Mary. The Hungry Leprechaun. [JP CAL]
Chase, Mary. The Wicked, Wicked Ladies in the Haunted House. [J CHA]
Edwards, Pamela Duncan. The Leprechaun's Gold. [JP EDW]
Kennedy, Richard. The Leprechaun's Story. [JP KEN]
Shub, Elizabeth. Seeing is Believing. [E SHU]
Shute, Linda. Clever Tom and the Leprechaun: An Old Irish Story. [JP SHU]
We have plenty more, too. Have a great day and watch out for the leprechauns!