Trifolium dubium

Trifolium dubium, the lesser trefoil, suckling clover, little hop clover or lesser hop trefoil, is a flowering plant in the pea and clover family Fabaceae. This species is generally accepted as the primary plant to represent the traditional Irish shamrock. It is native to Europe, but can be found in many parts of the world as an introduced species. It is probably an allotetraploid with 2n=32 that arose from the crossing of Trifolium campestre and T. micranthum....read more on Wikipedia.