Barter system was on this contenent way before any government was established, and is still legal exchange if accepted by all parties involved.
The Mint has two faces if it accepts paper currency from Fed. Reserve, which is neither legal or has the right to print money out of thin air and charge interest on each bill printed. Illegal in USA.
Silver coins have always had value as well as gold.
coins with .9999% silver are true coins of value .