The Collaborative International Dictionary of English v.0.48:

Poppy \Pop"py\, Poppyhead \Pop"py*head`\, n. [F. poup['e]e doll,
   puppet. See Puppet.] (Arch.)
   A raised ornament frequently having the form of a final. It
   is generally used on the tops of the upright ends or elbows
   which terminate seats, etc., in Gothic churches.
   [1913 Webster]