luck penny

noun2

1. •
   A coin carried or given for luck.

   • 'A kind harvest to you, John Dolan,' cried the postillion, 'and success to ye, Winny, with the quality. There's a luck-penny for the child to begin with,' added he, throwing the child a penny. — 1812
2. •
   (no longer used) A small sum of money given back for luck when paying.

   • I mean, had he not luckily exposed his legacy to jeopardy, having offered it as bounty-money and luckpenny to the patron — 1827