Xylophone Kids Tutorials contains :

Chopsticks
Amazing Grace
Angels We Have Heard on High
Au Clair de la Lune
Brahms' Lullaby
Camptown Races
Can Can
Cielito Lindo
The First Noel
Frère Jacques
Happy Birthday to You
Hush Little Baby
 Jingle Bells
Joy to the World
La Cucaracha
Lightly Row
London Bridge Is Falling Down
Mary Had a Little Lamb
Ode to Joy
Oh Susanna
Old MacDonald Had a Farm
Row Row Row Your Boat
This Old Man
Twinkle Twinkle Little Star
The Wheels on the Bus
When the Saints Go Marching In
5 Very Easy Christmas Songs

Source :
http://youcanplayit.com
https://en.wikipedia.org/wiki/Xylophone