According to legend, St. Patrick used the shamrock to represent what?
While it’s a sign of luck to find a four-leaf clover, the shamrock (also known as the three-leaf clover) is found all over the green fields of Ireland. According to legend, in the fifth century, St. Patrick used them as a symbol to help explain Christianity, with each leaf referencing a part of the Holy Trinity (Father, Son, and Holy Spirit).
Source: Time