Creative Commons Search
Creative Commons has created this really useful search engine that lets you search for resources that are CC licensed. The image search is the most useful. Attirbution required.
Getty Public Domain images
"The Getty makes available, without charge, all available digital images to which the Getty holds the rights or that are in the public domain to be used for any purpose. No permission is required." Attribution required.
Select tools,, then rights and then Creative Commons. If the tools search is missing, to to Google Images Advanced Search and there will be many options to narrow your search including usage rights.
Contains beautiful high resolution photos of black and brown people for free.
Free icons and stock photos on just about everything.
Contains thousands of clip art at no cost and no attribution required.
Contains the best free-stocked videos and photos. Attribution is appreciated but not required.
This is an excellent site for freely usable images.