Pexels is a search engine for free stock photos you can use today. This should be your go-to destination when searching for a photo for your next project, or anything.
Unsplash 5.0 is a massive online catalog of the best online wallpapers from top photographers and editors around the world, free for you to use for anything.
If you're looking for unique, authentic and sometimes imperfect stock photos - tookapic stock has all of that. Unique collection of photos from people running their 365 projects (one-photo-a-day journals). $39/mo or $99/y gives you unlimited access to more than 85.000 photos.