Mark 12:42 (KJV) - "And there came a certain poor widow, and she threw in two mites, which make a farthing."
Luke 21: 1-3 (KJV) - "And he looked up, and saw the rich men casting their gifts into the treasury. And he saw also a certain poor widow casting in thither two mites. And he said 'Of a truth I say unto you, that this poor widow hath cast in more than they all."
So - what were the two mites? No one knows with certainly, but many numismatists believe that they were prutot (singular - prutah) of Yehonatan (103-73B.C.) - better known as Alexander Jannaeus, king of Judea and high priest. In the Greek test the coin is a "lepton" - lepta in the plural - with the connotation of something thin and/or small. These small bronze coins (they are 12 - 20 mm. in diameter) circulated for many years and are known to have been in common use during the lifetime of Jesus.
After the Jewish return from Babylonian exile, probably 539/538 B.C., Palestine was a province of the Persian empire and Persian and Greek coins would have circulated, although coins as we know them, were still quite new, having appeared only around 640-600 B.C.
In 334 B.C. Alexander the Great invaded the near east, getting as far as northern India. Alexander died in 323 B.C. and his generals carved up his empire. Palestine was first ruled by Ptolemy I as part of Egypt - his coins and those of his successors were widely used. Egyptian rule in Palestine was overthrown in 198B.C. by Antiochus III of Syria, a member of the Seleucid dynasty, so-called for its founder, Seleucus, another of the land-grabbing generals.
The Ptolemys and the Seleucids were Greeks and so introduced Greek religion and customs into the conquered territories. Hellenizing of Palestine led to the suppression of Jewish observances and, 167 B.C., eventually desecration of the Temple. The result was rebellion. The revolt had some initial success - the cleansing of the Temple is still remembered in Hanukkah - but was crushed in a few years. Peace terms, though, were favorable to the Jews with freedom of worship granted and eventual political independence from Syria in 142 B.C. under the Jewish family dynasty known as the Maccabeans or Hasmoneans.
In 138 B.C. the Jewish high priest, Simon Maccabeus, was granted the right to coin his own money. He apparently did not use this privilege, but his descendants did. Simon's grandson, the Alexander Jannaeus mentioned above, struck coins and on them refers to himself as "king".
The small bronze prutot, poorly struck and often off-center on the flan, are still found. There are three common types: 1) obverse, an inscription within a wreath; reverse, two cornucopiae with a poppy fruit between them; (2) on the obverse a flower (probably a lily); reverse an anchor, probably symbolizing stability, and a common symbol on Syrian coins; (3) obverse an anchor; reverse either a star with rays or a wheel with spokes - depending upon how one perceives it. If it be a star, Alexander might have intended it to refer to the prophecy in Numbers 24: 17 - "A star shall come out of Jacob, and a sceptre shall rise out of Israel."
They are neat little coins and fun to have; a search on "ancient coins" or "Jewish coins", etc. will bring up dealers who carry them.