Pewter Brooch in Shamrock design. Legend: The Shamrock is a three leaved clover that grows in Ireland. It is said that while Patrick was preaching an open-air sermon on the Holy Trinity, and an old Druid began to heckle him, ridiculing the idea that the three divine beings could somehow be one. Patrick plucked a shamrock and, holding it aloft, replied, "Just as the three leaves of the shamrock are separate yet part of the whole so it is with the Trinity of the Father, Son and Holy Spirit." Today wearing the shamrock is an integral part of St. Patrick's Day celebrations.