However this is a list of free stock images, but all images on those sites may not be free, don't forget to check the license and terms of use on the actual site before you use those images on your projects.
http://abstractinfluence.com/forums/stock-photos-ac2.html
http://adigitaldreamer.com/gallery/
http://budgetstockphoto.com/index.html
https://www.canva.com/photos/free/
http://cepolina.com/freephoto/
https://createherstock.com/free-stock-photos/
http://dougitdesign.com/downloads.html
https://deathtothestockphoto.com/join/
http://flickr.com/creativecommons/
http://freeforcommercialuse.net/13/
http://freerangestock.com/index.php
http://free-images.gatag.net/en/
https://www.gettyimages.com/resources/embed
http://historicalstockphotos.com
http://highresolutiontextures.com
https://images.superfamous.com/
https://interfacelift.com/wallpaper/downloads/date/any/
http://photogen.com/free-photos/free-stock-photo-category/all/
http://photorack.net/index.php
http://public-domain-photos.com
http://public-domain-image.com
Sabuj Kundu - https://github.com/manchumahara
Mamun Srizon - http://dribbble.com/srizon
Shemul - http://fb.com/shemul13
Sinbad Konick's - http://fb.com/SinbadisSailor
BeDesigner Group - https://facebook.com/groups/bedesigner/
Stefan Pejcic - https://github.com/stefanpejcic