This site
http://www.pdinfo.com offers 3500 Free Songs and Music you can use. Music and lyrics written by an American author and published in 1922 or earlier are in the Public Domain in the United States. No one can claim ownership of a song in the public domain, therefore public domain songs may be used by everyone. PD songs may be used for profit-making without paying any royalties. If you create a new version or derivative of a public domain song, you can copyright your version and no one can use it without your permission. However, the song remains in the public domain, and anyone else can also make and copyright their own version of the same PD song.