Clover, more specifically those with four leaves

Sadly, I don't have any good pics of Trifolium repens, or red clover, besides this one.  And you can hardly see the leaves on it.  As the genus name implies, this plant typically has three leaves, but if you find one with four (a 1 in 10,000 chance) then you are said to be granted with good luck.   

 

Legend has it that the leaves on clover stand for hope, faith and love and if there's a fourth leaf, that stands for luck.  Why some specimens of Trifolium have that fourth leaf is still not fully understood.  The possible reasons include environmental conditions or a very recessive genetic marker.

In any case, have a lucky and happy St. Patrick's day!