I was looking for a place to download copyright free images that could be used commercially for book covers. I came across this article and have looked through many of the sites. While a few didn't give me the options I was hoping for, several did and I managed to find a dozen or so possible images for creating my book cover.
The authors state "Many of these photographs are free from copyright restrictions or licensed under creative commons public domain dedication. This means you can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
However, some photos may require attribution. We’ve done our best to identify which license they fall under but we still advise you to do your own research and determine how these images can be used." From what I've seen they have done a good job of verifying license and attribution info and I double checked some just to see how accurate they were and they were on the money with each. Many seem to have very similar photos for the same search term but some have some truly unique images.
there doesn't seem to be anything here