Check out this article on photography and graphic design. In this photo gallery, you'll find wood grain pictures, pictures of rust, and other texture photographs.
Rope Textures
© Karen ChappellSunset
© Katarina ManssonRusty and Crusty from Travel
© Marilyn CornwellVolcanic Landscape of Bromo
© Ujjwal MukherjeeCamp Site #3
© Jack GaskinClogs on Cogs
© Nikki McDonald