Images that are in the
PUBLIC DOMAIN
(copyright free, you can use without permission)
​

https://www.pexels.com/public-domain-images/

https://free-images.com/

https://www.publicdomainarchive.com/

https://creativecommons.org/

https://www.flickr.com/search/?text=british%20museum%20public%20domain

https://pmp-art.com/

https://pixabay.com/

(For some really awesome collections of prints, patterns and designs, search Flickr for "public domain ornament)"