So how do you find material that can be used without permission? Google's Advanced Search offers a special search limiter on usage rights that can help. Input your search terms, then scroll to the bottom of the page and select the usage right that applies to how you want to use the material you find:
- free to use or share
- free to use or share, even commercially
- free to use, share, or modify
- free to use, share or modify, even commercially
Be aware that much more will be available for non-commercial than for commercial use.