My bonny lass she smileth is a famous English madrigal, written by Thomas Morley and published in 1595. It is based on an Italian madrigal, published by Gastoldi in 1591 (see ref 1 and supporting recording). The ChoralWiki gives the following words for the two opening verses.
The song was parodied by Peter Schickele (http://www.schickele.com/composition/twomadrigals.htm) (writing as PDQ Bach) as:
Phillip Ledger (ed) The Oxford Book of English Madrigals (1978) Oxford University Press, and co-issued recording, by Pro Cantione Antiqua