This is a Yiddish folk song written by the songwriters Aaron Zeitlin, Sholom Secunda, Arthur Kevess and Teddi Schwartz in 1940. It is also known as "Dona Dona" but it is not about a girl, but a calf on the way to market about to be slaughtered. Some see this as a metaphor for Jews in the Holocaust.
This song was made popular by Joan Baez, who sang it on her debut album in 1960. Donovan also recorded this song on his debut album in 1965.
Suggestion credit: Sara - Silver Spring, MD, for above 2