mother goose

from WordNet (r) 3.0 (2006)

Mother Goose
    n 1: the imaginary author of a collection of nursery rhymes

from The Collaborative International Dictionary of English v.0.48

Mother Goose \Mother Goose\ n.
   The supposed author of a book of nursery rhymes first
   published as "Mother Goose's Melodies," and usually called
   simply "Mother Goose." The first English edition is said to
   have been printed in 1719 in London. The actual persons who
   composed the rhymes is unknown, and earlier similar rhymes in
   French are a likely source for some of them. Mother Goose is
   also used as the title of a book of Mother Goose rhymes.
   [PJC]