St. Patrick and the Pagan Snakes of Ireland:
St. Patrick is known as a symbol of Ireland, particularly around every March. One of the reasons he's so famous is because he supposedly drove the snakes out of Ireland, and was even credited with a miracle for this. Some people believe that the serpent was actually a metaphor for the early Pagan faiths of Ireland. It's important to note that he did not physically drive the Pagans from Ireland, but instead St. Patrick brought Christianity to the Emerald Isle. He did such a good job of it that he began the conversion of the entire country to the new religious beliefs, thus paving the way for the elimination of the old systems - and this was a process that took hundreds of years to complete.
Over the past few years, however, many people have worked to debunk the theory of Patrick driving early Paganism out of Ireland, which you can read more about over at The Wild Hunt. Paganism was active and well in Ireland both before and after Patrick came along, according to scholar Ronald Hutton, who says in his book Blood & Mistletoe: A Pagan History of Britain, that "the importance of Druids in countering [Patrick's] missionary work was inflated in later centuries under the influence of biblical parallels, and that Patrick’s visit to Tara was given a pivotal importance that it never possessed..."
Pagan author P. Sufenas Virius Lupus says, "St. Patrick’s reputation as the one who Christianized Ireland is seriously over-rated and overstated, as there were others that came before him (and after him), and the process seemed to be well on its way at least a century before the “traditional” date given as his arrival, 432 CE." He goes on to add that Irish colonists in numerous areas around Cornwall and sub-Roman Britain had already come into encountered Christianity elsewhere, and brought bits and pieces of the religion back to their homelands.
And while it's true that snakes are hard to find in Ireland, this may well be due to the fact that it's an island, and so snakes aren't exactly migrating there in packs.
The real St. Patrick was believed by historians to have been born around 370 c.e., probably in Wales or Scotland. Most likely, his birth name was Maewyn, and he was probably the son of a Roman Briton named Calpurnius. As a teen, Maewyn was captured during a raid and sold to an Irish landowner as a slave. During his time in Ireland, where he worked as a shepherd, Maewyn began to have religious visions and dreams -- including one in which showed him how to escape captivity. Once back in Britain, Maewyn moved on to France, where he studied in a monastery. Eventually, he returned to Ireland to "care and labour for the salvation of others", according to The Confession of St. Patrick, and changed his name to Patrick, which means "father of the people."
Today, St. Patrick's Day is celebrated in many places on March 17, typically with a parade (an oddly American invention) and lots of other festivities. However, some modern Pagans refuse to observe a day which honors the elimination of the old religion in favor of a new one. It's not uncommon to see Pagans wearing some sort of snake symbol on St. Patrick's Day, instead of those green "Kiss Me I'm Irish" badges. If you're not sure about wearing a snake on your lapel, you can always jazz up your front door with a Spring Snake Wreath instead!