The Collaborative International Dictionary of English v.0.48:

Sunflower \Sun"flow`er\, n.
   Any plant of the genus Helianthus; -- so called probably
   from the form and color of its flower, which is large disk
   with yellow rays. The commonly cultivated sunflower is
   Helianthus annuus, a native of America.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sunflower
    n 1: any plant of the genus Helianthus having large flower heads
         with dark disk florets and showy yellow rays [syn:
         sunflower, helianthus]

U.S. Gazetteer Counties (2000):

Sunflower -- U.S. County in Mississippi
   Population (2000):    34369
   Housing Units (2000): 10338
   Land area (2000):     693.790221 sq. miles (1796.908346 sq. km)
   Water area (2000):    13.425227 sq. miles (34.771176 sq. km)
   Total area (2000):    707.215448 sq. miles (1831.679522 sq. km)
   Located within:       Mississippi (MS), FIPS 28
   Location:             33.587683 N, 90.583678 W
   Headwords:
    Sunflower
    Sunflower, MS
    Sunflower County
    Sunflower County, MS


U.S. Gazetteer Places (2000):

Sunflower, MS -- U.S. town in Mississippi
   Population (2000):    696
   Housing Units (2000): 242
   Land area (2000):     0.404824 sq. miles (1.048489 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.404824 sq. miles (1.048489 sq. km)
   FIPS code:            71600
   Located within:       Mississippi (MS), FIPS 28
   Location:             33.545397 N, 90.537595 W
   ZIP Codes (1990):     38778
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Sunflower, MS
    Sunflower