Saint David was an Archbishop of Menevy. He was descended from the royal house of Ceredigion. He lived a long life - claimed to be one hundred and forty years - that spanned the Fifth and Sixth Centuries. St. David founded the monastic community of Glyn Rhosin in the westernmost county of Pembrokeshire. He is noted as being the patron saint of Wales. The holiday was primarily celebrated by the Welsh.
There is one curious tradition that distinguishes this holiday: the wearing of leeks in one's hat. The leek is a vegetable related to garlic and onions. The leek has a white, bulbous root end with long, dark green leaves.
This tradition came about as Saint David encouraged the Britons under King Cadwallo, then being hassled by the Saxons, to wear leeks in their hats so as to be more noticeable in battle. During one such battle, on 01 March, the Britons wore the leeks in their hats and were victorious; and so thereafter they and their descendants wore leeks in their hats on the anniversary of the battle.
Saint David is believed to have died on 01 March 589, and therefore many believe that it is the saint's death date that is honored by this holiday.
Richard Rolt, in his 1759 publication, Cambria, a Poem in three books, presented the following verse:
In Cambria, 'tis said, tradition's tale
Recounting, tells how fam'd Menevia's Priest
Marshalled his Britons, and the Saxon host
Discomfited; how the green Leek the bands
Distinguished, since by Britons yearly worn
Commemorates their tutelary Saint.
It was customary for celebrants on St. David's Day to eat Welsh Stew, commonly called cawl, which was composed of lamb (or beef, pork or bacon) mixed with potatoes, carrots, celery and turnips, and of course, leeks.
The English, who were primarily descended from the Saxons who met defeat at the hands of the leek~wearing Welsh/Britons, scorned the holiday. They did not simply dislike it and refrain from celebrating it; rather, they created their own traditions including hanging Welshmen in effigy. Samuel Pepys, in his Diary of 1667, noted: "In Mark Lane I do observe (it being St. David's Day) the picture of a man dressed like a Welshman, hanging by the neck, upon one of the poles that stand at the top of one of the merchant's houses in full proportion, and very handsomely done, which is one of the oddest sights I have seen a good while, for it was so like a man that one would have thought it was indeed a man."
English bakers established a tradition in the baking of gingerbread men (called taffies) which were made to look like a Welshman, either who had been skewered on a spit or was riding on a goat. The name of taffy came from the diminutive form of the proper name, David.