White clover (Trifolium repens), also known as Dutch clover, is a perennial legume species native to North America, West Japan and Europe. Today, white clover is found worldwide and is a highly nutritious forage legume crop for livestock.

More information and data available at:
USDA-NRCS White Clover Fact Sheet
White clover Marker Database
Clover Garden
Image Source: http://en.wikipedia.org/wiki/Trifolium_repens#/media/File:Starr_070313-5645_Trifolium_repens.jpg