white clover

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A common European clover (Trifolium repens) widely naturalized in North America, having rounded white flower heads.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a species of clover, Trifolium repens, native to much of Europe, North Africa and parts of Asia and introduced elsewhere as a pasture crop.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun creeping European clover having white to pink flowers and bright green leaves; naturalized in United States; widely grown for forage