I have been making small numbers of premium Adobe stock images available to my client base. That offer is still open, if you want to take a look at the library which is huge with millions of images available.
I have also come across the following list of sites which offer free images. You need to check the details of each, but of the one or two I have looked at, they do look useful. The article that led me to this was sitting in the dashboard of my WordPress site. You can read the WP Tavern blog (All about news relating to WordPress here: https://wptavern.com/13-sources-for-free-public-domain-and-cc0-licensed-images )
You can access these sites by clicking on the links below:
- https://unsplash.com/
- http://www.publicdomainpictures.net/
- https://pixabay.com/
- https://www.splitshire.com/
- http://www.1millionfreepictures.com/
- http://viintage.com/
- http://littlevisuals.co/
- http://pdpics.com/
- https://www.flickr.com/photos/britishlibrary/
- http://nos.twnsnd.co/
- http://pickupimage.com/
- http://publicdomainarchive.com/
Before you do commit to using anything on your website from this list. Do check the licence prevailing for the image and make sure there is no payment, implied or otherwise relating to it if you wish to use it for free.