OK, she's not the patron saint of butter. I mean, she should be--if anyone in the Vatican is reading this, we could use a patron saint of butter. She is, however, the patroness of milkmaids, and one story about her tells us about her powers over butter: young Brigid once gave a poor man her mother's entire stock of butter, but the butter was miraculously replaced before Brigid's mother found out (I don't know about you, but I'd definitely notice if all my butter was missing).
St. Brigid is one of the patrons of Ireland, along with St. Patrick and St. Columba, and she an exciting life story. Most of the stories agree that she was born into slavery, because her mother was a slave (her father was a chieftain, and his wife forced him to sell Brigid and her mother after Brigid's birth). As a baby, she refused to be fed by a Druid because he was "unpure"--instead, she suckled from a red and white cow. From a young age, she showed special care for the poor , as seen in the butter story, and many miracles are attributed to her, even during her life.
She became a nun and founded a monastery at Kildare in 480. She also founded a school of art and a scriptorium.
Her feast day is February 1 and besides being a patron of Ireland, she is also the patron of poultry farmers, babies, blacksmith, dairy maids, dairy workers, fugitives, and midwives.