Pixabay

Pixabay is a public domain that hosts free images.  Once you search for an image that you need, you download the images that are below the row of shutterbox images; these are free. 
 http://pixabay.com/en/

Image After.........Free Stock Images

Image After: 

Free stock images that students can use to create multimedia projects.

 http://www.imageafter.com/

More Free Stock Photos

Free stock photo search engine:  http://www.veezzle.com/  

and http://www.picsearch.com/

Free Stock Photos

Free stock photo and clip art sites:
http://www.freephotobank.org/main.php

http://www.school-clip-art.com/

Flickr

Flickr is a photo sharing site.  Within the site, there is a creative common section that students can go under.  Students can use these pictures for school projects.

Free Clip Art

Royalty Free Public Domain Clip Art
http://www.clker.com/

Free Stock Images

Stock images from 10 categories
http://www.turbophoto.com/Free-Stock-Images/

Pictures for Projects--FREE

When teaching about copyright we talk about what public domain is. One of several sites that I mention is ookaboo. This site offers free pictures of everything on Earth.

http://ookaboo.com/o/pictures/

Another site to try is http://pics4learning.com/

Students can use these pictures on web sites and for classwork: It is copyright-friendly for anyone to use.