widow's mite

noun2

1. •
   A very small gift or donation which, however, represents a great sacrifice on the part of the giver.

   • What are the sinews and souls of Russian serfs and Republican slaves but Fast-Fish, whereof possession is the whole of the law? What to the rapacious landlord is the widow's last mite but a Fast-Fish? — 1851
2. •
   The lepton coin.