neckar nut

from The Collaborative International Dictionary of English v.0.48

Nicker nut \Nick"er nut`\
   A rounded seed, rather smaller than a nutmeg, having a hard
   smooth shell, and a yellowish or bluish color. The seeds grow
   in the prickly pods of tropical, woody climbers of the genus
   {Caesalpinia}. {Caesalpinia Bonduc} has yellowish seeds;
   {Caesalpinia Bonducella}, bluish gray. [Spelt also {neckar
   nut}, {nickar nut}.]
   [1913 Webster]