Hi. I started to reply to this but ran into difficuties with constructive advise, so have started again
This much is true: You can make searches for Licenced material, as follows
Audio: Creative commons or Weedshare
Images: Creative Commons, FDL, GPL, Artistic or Public Domain
Documents: Creative Commons, FDL, GPL or Public Domain
Programmes: Creative Commons, Shareware, Apache or BSD, X or MIT, GPL or LGPL, or Public Domain
However the results do not give you much to go on in practice. Audio Search with Creative Commons is the most promising, but most licences are fake. This you can see by right clicking on the file and selecting view licence, although you can also hover over the file with extended tooltips enabled, and see the details in "comments".
You best way to find legally downloadable material is to go to sites like
www.magnetmix.com or
www.creativecommons.org or
www.weedshare.com or possibly
www.archive.org and see what is available. You will in many cases find a Magnet link which you can use which will download in Limewire.
Phex in addition supports Magma links, all to fully legally downloadable material through their Polar Skulk. This is fairly new, and as yet is exclusive to Phex.
I have not been much help I know, but you have prompted me into looking more closely at this, and I am learning as you are