Question: In Matthew 27:9 it says, "Then was it fulfilled that which was spoken by Jeremy the prophet, saying, and they took the thirty pieces of silver, the price of him that was valued" ... I cannot find this anywhere in the book of Jeremiah.
Answer: If you will notice carefully, the verse states it was spoken by Jeremiah. It does not say it was written.
The Gospel of John explains why it would be impossible for everything prophetic or fulfilled to have been written:
"And there are also many other things which Jesus did, the which, if they should be written every one, I suppose that even the world ITSELF COULD NOT CONTAIN THE BOOKS THAT SHOULD BE WRITTEN." - John 21:25