Do not scratch you computer screen I used to have Corel Painter software, was great to create "textures", but as I changed computer I did not reinstalled it, I prefer traditional painting for textures (way far more easier than in digital ! hahaha).
I use 'found' textures almost exclusively as machine generated textures or 'filters' betray their originas too easily. I do use machine textures and filters on top of the found textures, sometimes, but aesthetically satisfying results can be hard to come by. In 'The Phantlers Suggestion' [link] I applied a whole gamut of 'texture' filters to a single colour inverted photo. I think you can see from the result why I don't do this kind of thing all that often.