While I am searching for pictures of brains (so far without success) I was thinking that others might be looking for sources of pictures they can use as well.
Best of free stock photos
Here are my picture resources, in no particular order:
1. Unsplash
I would describe this site as artsy. Wonderful pictures, some very professional looking.
https://unsplash.com/
2. Refe Real Life Photos
The name says it all...
http://getrefe.tumblr.com/
3. picjumbo
Free and premium membership.
https://picjumbo.com
4. Morguefile
Another huge collection. Not all pictures look professional. Lots of "people" photos.
https://picjumbo.com
5. Pixabay
Images, vectors, and videos.
https://pixabay.com/
6. Death to the stock photo
Lovable, artsy, different.
http://deathtothestockphoto.com
7. Little visuals
8. Gratisography
Very interesting pictures. Great for articles.
http://www.gratisography.com/
9. Compfight
With search engine.
http://compfight.com/
10. Splitshire
Very many professional looking pictures
http://www.splitshire.com/
11. IM creator
Curated. Also includes templates, icons ...
http://www.imcreator.com/free
12. New Old Pictures
Vintage Photos
http://nos.twnsnd.co/
13. PhotoPin
Millions of creatives
http://photopin.com/
14. Function
Smaller but nice collection. More than pictures.
15. Free High Resolution Photos
Receive 20 pictures per email when you sign up and more every Sunday
https://pjrvs.com/a/photos/
16. Dreamstime
By far the biggest site on this list. You can also sell your own pictures on there. Free and paid pictures (subscription).
https://www.dreamstime.com
