Openverse is the replacement for the old CreativeCommons.org search tool. The Creative Commons organization has handed-off oversight of Creative Commons search to WordPress. WordPress now operates Creative Commos search as Openverse.
Openverse can be used to find Creative Commons-licensed and public domain pictures and audio files. The best aspect of Openverse is that it provides a clear explanation of how you can and can’t use a particular image or audio file. It also provides preformatted text to use when citing the source of an image or audio file.