I'm not sure if that's exactly what you're looking for, but when you go to Google Images looking for something and click Tools, you can pick an option that says "usage rights" and then pick from available options that are listed by usage rights. After the page reloads, everything shown will be available with the respective option. A lot of these will allow to freely use an image without the need to credit the source (at least the ones I dug up had that information right next to them)