Clover

Myths, folklore, & symbolism
Clover: It is a widely distributed papilonaceous flower. Because of its vigorous growth, it is a sign of vital energy. For the Celts it was a sacred, magical plant. In the Middle Ages, clover was a Trinity symbol because of its three leaflets; as a medicinal plant, it sometimes referred to Mary. The four-leaved clover is still seen as bringing good luck; however, clover with more than four leaflets is usually considered unfavorable. The five-leaved clover, however, sometimes points to a happy marriage. (Herder)