These are copyright-free stock textures.
Feel free to use them in any of your work, personal or commercial...and don't worry, no credit is needed. If you do something cool with the images, I'd be more than happy to check it out, so hit me up with a link.
All the images are 3072x2048, so they should be big enough for whatever you may need them for. They are in a zipped file...
If you'd like some more textures just like these then check out Lost and Taken