From "The Annotated Mother Goose", a fabulous book by Baring-Gould, pub. 1962 (look for it used):
A thin pudding made of pease meal. This rhyme is both a riddle and a clapping game, played by children on cold days to keep their hands warm. The first four lines and th final couplet were first published c. 1765 in Newbery's "Mother Goose's Melody," where the editor appended this maxim to the rhyme: "The poor are seldom sicker for want of food, than the rich by the excess of it."