When looking through the 93 "Chestnut" images at Acclaim Images.com this Conker on a Piece of String on a Black Background 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:
Conker on a Piece of String on a Black Background
Studio close up stock photo of a conker on a piece of string.

Some related terms for more images:
spiky,  chestnuts,  english horse chestnut,  hippocastanaceae,  fruits,  aesculus,  conker,  string,,  autumnal,  conker on a string,  ripe,  spike,  horse chestnuts,  spikes,  english horse chestnuts,