Offering creative commons photos

I am doing a little research because I am interested in exploring creative commons resources. I am particularly interested in photos. I know that Google offers a great service to search for photos offered under creative commons licenses. I am interested in the opposite end of the creative commons relationship. How do I offer creative commons images? I know I can do this with Flickr, but I think I pay $60 a year for my Flickr account and this cost may put this service out of range for classroom use. Google+ used to have a way of doing this, but Google+ is gone. I don’t know of a way to do this with Google photos.

Am I missing something? Any comment would be appreciated.

This Creative Commons site offers suggestions for offering resources with CC licenses, but lists only Flickr and Europeana for photos.