If you're entirely new to OER, or you'd like more information about copyright, finding OER, teaching with OER or publishing OER, try the OER Starter Kit from Iowa State University.
You can use this meta finder to search all the collections below at once, or you can go into each collection separately.
Collections indicated with an asterisk (*) are the recommended places to start.
The Public Domain Project, founded by Pond5, is a collection of multiple file types all within the public domain, including video footage, music tracks, sound effects, after effects, photographs, illustrations, and 3D models.