From the recording Sumer Is Icumen In

Sarabande performs this early 13th-century round as an instrumental, although Matt sometimes sings it at his solo appearances.

Lyrics

Sumer is icumen in, lhude sing cucu
Groweth sed and bloweth med and spring'th the wud enu
Sing cucu
Awe bleteth after lamb, lhuth after calve cu
Bulloc sterteth, bucke verteth, murie sing cucu
Cucu, cucu
Wel singes thu cucu, ne swik thu naver nu.