Ive been using a range of texture in my work for many years now and Ive had a folder on the hard drive stuff with scans and photos. These have been slowly built up over the years and I over 90 high res images that I was starting to get a little tired of (and a whole stack of new things to scan). Ive just made all of them available on a Creative Commons licence from Flickr here.
Heres some more of my favourite and most used:
