A well assembled post on stock photos! Pixabay is the largest free resource. I hadn't heard of canvas before. As others have said you can do a Google search and refine your results to include royalty free images.

I have done a small study on the lack of diversity in stock photography. I'd love to get others feedback and opinion on this issue: https://steemit.com/race/@doyoueatdolphins/color-in-stock-photography