My favorite go-to place for the best free images is Unsplash. A recent change caused some confusion over the use of them however. But all is well.
Unsplash Updates its License, Raises GPL Compatibility Concerns
Luke Chesser, co-founder of Unsplash, explained on Twitter that individual photos are still CC0-licensed and therefor GPL compatible.
“The Unsplash license doesn’t violate GPL and can still be used in WordPress themes,” Chesser said. “There are no restrictions on the individual photos.
“There is only a restriction on the collection of photos, which doesn’t even apply unless your intent is to create a similar service.”