Free non-copyrighted banners

Hey I made a simple search and could not find anything. Where can I get free non-copyright banners theres a couple simple ones out there with just a car and nice background, but its probably copyright. Where can I get free ones non-copyright, or atleast non-copyright photos. Nowadays you can get in trouble for using any picture you find.

Google images has a filter in the advanced search that allows you to filter by license type.