What happened to Judas 30 pieces of silver?

In Matthew 27:3 it states: When Judas who had betrayed him, saw that Jesus was condemned, he was seized with remorse and returned the 30 silver coins to the chief priests and the elders. "I have sinned" he said, "for I have betrayed innocent blood." Judas threw the money int the temple and left. Then he went to hang himself.

The chief priest picked up the coins and said " it is against the law to to put this into treasury since it is blood money" So they decided to use the money buy the potters field as a burial placer for foreigners. That is why it is called the Field of Blood to this day.