Saint David was born in Wales and was the son of King Sant in South Wales.  Ordained a priest and bishop David ministered in Wales.  He is reported to have been instrumental in the battle against the heresy of Pelegianism.  He founded many monasteries and is the patron saint of Wales.  Brigid at Under the Oak posts about the link between St. David and Ireland in her post on the Saints of March. Also see her other post of a paper about the Irish devotion to St. David of Wales.

"The importance of St. David's life shows itself in the story of how his birth was foretold to his father.  Here is a quote from a translation of Rhygyfarch's Life of St. David by ....For on a certain occasion, his father, Sant by name and merits, who relied on his royal power over the people of Ceredigion, which subsequently he laid aside to procure a heavenly kingdom, was warned in dreams by an angelic voice, which he heard, "To-morrow on waking thou shalt go hunting, and having killed a stag near a river, thou shalt find there three gifts by the river Teivi, namely, the stag which thou pursuest, a fish, and a swarm of bees settled in a tree in the place which is called Llyn Henllan. Of these three, therefore, reserve a honeycomb, a part of the fish, and of the stag, which send to be kept for a son, who shall be born to thee, to the Monastery of Mattcannus" which till now is called the Monastery of the Deposit. These gifts foretell his life, for the honeycomb proclaims his wisdom, for as honey in wax, so he held a spiritual mind in a temporal body. And the fish declares his aquatic life, for as a fish lives in water, so he, rejecting wine and beer and everything that can intoxicate, led a blessed life in God on bread and water only, wherefore David is also named " of the Aquatic Life." The stag signifies his power over the Old Serpent, for as a stag, having deprived serpents of their food, seeks a fountain of water and is refreshed as in youth with the strength received, so he, borne on high as on stags' feet, deprived the Old Serpent of the human race of his power of hurting him and fled to the fountain of life with constant Sowings of tears, and, being renewed from day to day, so brought it to pass that in the name of the Holy Trinity, by the frugality of moderate repasts, he began to have saving knowledge [and] the power of governing demons."

See the Catholic Encyclopedia for more details on St. David.

Also the Life of St. David