You can get many from the following links:
http://www.freeimages.com/
http://search.creativecommons.org/
http://photopin.com/
http://commons.wikimedia.org/wiki/Main_Page
http://www.stockphotosforfree.com/
https://openclipart.org/
https://unsplash.com/
http://superfamous.com/
https://picjumbo.com/
http://pixabay.com/
http://www.imcreator.com/free
http://www.gratisography.com
http://www.morguefile.com/
http://littlevisuals.co/
http://nos.twnsnd.co/
http://picography.co/
http://getrefe.tumblr.com/
http://publicdomainarchive.com/
http://creative-commons.deviantart.com/
http://freerangestock.com/
http://animalphotos.info/a/
http://carpictures.cc/cars/photo/
http://www.clker.com/