The lyric “Its fleece was white as...” is completed by “snow” in “Mary Had a Little Lamb.”
The line describes the lamb’s exceptionally white wool and establishes the rhyme’s gentle, idealized opening image. In the familiar verse, Mary’s lamb follows her everywhere, eventually turning up at school even though bringing an animal there breaks the rules.
The poem is generally associated with Sarah Josepha Hale, who published it in 1830. The song became one of the best-known American children’s pieces, with later versions sometimes changing wording or adding repeated lines. “Fleece” refers to the woolly coat of a sheep, so “wool” may sound plausible but is not the traditional lyric.
The song also has an important recording-history connection. In 1877, Thomas Edison used the opening lines to test his phonograph; the performance is widely regarded as the first successful recording and playback of the human voice. That event helped make this simple nursery song part of early sound-recording history.