Royalty free images truly royalty free stock photos not some thing that make you sign up and then start charging as soon you use their free stock photos. You may use Google search to find the free images for you but when you consider the copywright issue in mind the whole business is not worth the trouble.
It is even better if you opt to shoot your own picture and use and free to host website to host them and use them on your website. If you have your own server then it is better you can store it on it also
Jeez, there are sure a ton of ways to find images on the Web, as well as many places where you can find lengthy link lists to image collections.
I’d lay odds that most people, including myself, just use Google Image Search when they need to find an image. However, there might be instances when you want to use another tool — perhaps you’re a language teacher searching for just the right clip art or photography to illustrate a verb, maybe you have very young students and are concerned about what they might find on Google,  possibly you’re particularly teaching about copyright issues, or you want your students to easily connect an image to a writing exercise and have them send an E-Card. (Google has recently added an option in their advanced image search feature — go to the bottom left under “license” and choose “labeled for reuse”)

Searching the images by Creative common  licence. and what you may find expecting a image under the category
 Flick Creative Common can be used to find free source of images, the only thing is to check is when you find a image just check out the ADVANCE SETTING and see it is coverd under Creative common license or you may have a issue about it later.
Another way to search creative common license image is 

Nations Illustrated has 7300 images oon their collection and you can update their database with yours too I did around 200, and they have E-Card feature.

 Royalty Free Clip Art Collection from Purdue University is a good English teacher and find clip arts if you are looking that way
 Japanese Language Course  is similar to above but also have image on their webhost the main site is Jap
Pics 4 Learning Use over 5000 images hosted on their website however the main scope is designed for eductation people only.
Clip Art ETC  Another 55000 pics from Florida’s Educational Technology Clearinghouse for students and teachers
Edupics  another source for clip arts has over 2 million pics online registration required
 Morgue File  both premium and free images are here but their collection is small
I’m also adding a direct link to Darren Draper’s excellent post (including additional resources) called The Educator’s Guide To The Creative Commons.

 Wikimedia Commons license says
almost all may be freely reused without individual permission according to the terms of the particular license under which it was contributed to the project. Depending on what you want to do with it, you probably do not need to obtain a specific statement of permission from the Licencor.

Free Foto: 132449 images and all are great that is what I found when I checked it out ” they also promote low cost royalty free images from shuttersotck dot com on their website
Free Digital Photos:  This guy has registration for contributor as well as user separte i guess they have some thing in mind to make money in future more of a search engine to me
Public Domain Photos: 13200 pics alltogeter, ok to use
Free Historical Stock Photos“ If you are fond of History this is the best place to pic your photos no registration
Big Fotocom  a new bee in the industry no registration
Photos 8 another new bee with good quality pics no registration

Heritage Explorer Hundred of British island images
World Images, Over 1 million of images in their database to be used

All Our Stock another source of royalty free image

WP Clip Art ... clip arts specialist.”
 Picapp millions of images
The Open Clip Art Library  hand made cliparts
 Nasa collection of photos without no copyright restrictions, know more about it at the Los Angeles Times.

Wylio  allows you to find a cc licensed photo with the option to resize it and use it on your blogs
ookaboo  have both free and premium images to be used
,ore Free Images has 7000 original stock photos to be used with a linkback credit to the site 
Picture Of A is a new site where “all photos are completely free to use and are open source!.
Finding and using public domain photographs Advice tips and images all in one place 
The Noun Project collection sybols clips and images good one
PD Photo has photos majority on public domain
4 Free Photos is another website that offers a good selection of public domain images.
This is a nice post about the Flickr Creative Commons Search tool.
Image After over 1 million pics last time i checked Richard Byrne’s blog).
ELT Pics by twitter to collect pics for english teacher.
Copyright Free and Public Domain Media Sources another source or over 3k  images
Kozzi with free registration you can use their images with a link back to their site, The images are of good qulaity and are royalty free
PhotoPin a search engine best on images which allows you download the images and use it under ccc and tell you how to do it read more about the site at their post.