Arirang

This haunting Korean folk tune has been sung for over six hundred years.  Dr. Campbell suggests pairing it with a traditional changgo drum pattern.

Source: Campbell, Patricia Shehan. Tunes and Grooves for Music Education. p. 25

Mary Wore Her Red Dress

There is a great book by Merle Peek that goes with this song.  It's also a fun one to sing at Halloween time, when children can sing about the costume they wore, or would wish to wear.
Source: R. C. Seeger.  American Folk Songs for Children

Hi! Ho! The Rattlin' Bog

It's fun to see how fast students can tear through this cumulative Irish song.  Visuals will help you keep track of where you are in the song as it grows longer and longer.
Sources: Ed. by Eisen, Ann and Robertson, Lamar.  An American Methodology: An Inclusive Approach to Musical Literacy p. 331
Langstaff, John.  Hi! Ho! The Rattlin' Bog and other Songs for Group Singing