The Shamrock
The shamrock is a common name for a three-leafed clover native to Ireland. The Irish have considered shamrocks as good luck symbols, and today people of other nationalities have also adopted that belief. It has become the national symbol of Ireland, because of the legend that St. Patrick used it to illustrate the doctrine of the Trinity.
Preaching on the doctrine of the trinity, he is said to have illustrated the existence of the Three in One by plucking a shamrock from the grass growing at his feet and showing it to his congregation. It symbolizes the cross and blessed trinity.