The Collaborative International Dictionary of English v.0.48:

Tilley \Til"ley\, n., or Tilley seed \Til"ley seed`\ (Bot.)
   The seeds of a small tree (Croton Pavana) common in the
   Malay Archipelago. These seeds furnish croton oil, like those
   of Croton Tiglium. [Written also tilly.]
   [1913 Webster]