Songbooks:
The Great Family Songbook by Dan Fox and Dick Weissman. Easy piano accompaniments plus guitar chords.
The American Song Treasury – 100 Favorites by Theodore Raph. Easy piano accompaniments plus guitar chords. Includes history of each song.

Sources for beginning a classical music collection:
Keeping the Beat CD, John Feierabend
Top 100 Classical– top 100 Classical works

Videos:
The Nutcracker / Baryshnikov, Kirkland, Charmoli (1977)
Move It! Expressive Movements with Classical Music (DVD) with Peggy Lyman/John Feierabend
Mr. Bach Comes to Call (DVD; originally a CD)
Beethoven Lives Upstairs (DVD; originally a CD)

CD songs:
Burl Ives Sings Little White Duck (And Other Children's Favorites)
Peter, Paul and Mommy
Judy Collins, Peter Paul & Mary, Simon & Garfunkel, Arlo Guthrie, Woodie Guthrie – all part of American folk revival

CD series for listening:
Keeping the Beat (John Feierabend)

Classical Kids series – excellent resource (The Children's Group), including:
Mr. Bach Comes to Call CD
Beethoven Lives Upstairs CD
Vivaldi’s Ring of Mystery CD
Mozart’s Magic Fantasy: A Journey through the Magic Flute CD