I thought it was a Girl Scout standard from long ago. I have a first edition (1949) of Sing Together from the Girl Scouts, and it doesn't have the song. It does appear in the third edition (1973), which says it's traditional, taken from the 1966 edition of Exploring Music 4 (Holt, Rinehart, Winston). Exploring Music says it's traditional and doesn't give any more information.
So, that takes it back to 1966, the year I graduated from high school. I guess that's ancient history - at least my kids think it is.
-Joe Offer-