I have posted some brick wall and stone textures before, but here is another and more comprehensive set of such stock photos:
As usual, you can download the high resolution images (for free) by clicking on the low-res pics. Natural brick wall textures contain quite a bit of detail, so downloading may be a bit slow.
From a design point of view - aren´t these colorful old brick walls beautiful?
The image below contains two rusty nails - thought I include it here among the textures, see what you can do with it:
(If you are looking for photos of rust or grunge textures btw, check out the free stock images of rusty metal.)
After some close-up photographs a few pictures of large brick walls - they make good backgrounds.
Many of the old brick walls here are built with handmade bricks; the last one of each day was usually marked by the worker (not sure what to make out of it, though):
Within a few miles, one comes along a huge color range with all different kinds of red:
Look at the variety of red color in this image: