Wiktionary
widow's mite
n. 1 A very small gift or donation which, however, represents a great sacrifice on the part of the giver. 2 (label en numismatics) Name given to the lepton coin.
Usage examples of "widow's mite".
London's credit-machines clicked for the vaporous profits of gambling as readily as they did for the widow's mite.
I will make the Widow's Mite into the kind of Corporation we can both be proud of.
A military undertaking that had strained the resources of the entire arrayed might of the house of Habsburg, with all their imperial dominions and an annual treasure fleet from the Americas was beyond the pope's means to put in any more than the proverbial widow's mite.