When looking through the 607 "Sunflower" images at Acclaim Images.com this A Sunflower Portrait was a favorite.
All of their pictures are hand picked, availiable in a number of formats, and you can even get custom prints and posters.

Description:
A Sunflower Portrait
Stock photo of large colourful fields of sunflower blooms in the summer near Brandon, Minnesota, USA.

Some related terms for more images:
sunflower crop,  field,  agriculture,  crops,  country side,  sunflowers,  sunflower field,  sunflower fields,  sunflower crops,