Original U.S. Constitution
Art. I Sec. 8 Cl. 5
[Congress shall have Power ... ] To coin Money, regulate the Value thereof, and of foreign Coin, ...;
Art. I Sec. 10 Cl. 1
[No State shall ...] make any Thing but gold and silver Coin a Tender in Payment of Debts; ...
the United States Constitution clearly states that the only thing a state shall issue for its currency is gold and silver. it is for this very reason that the state of Washington should have the full legal right to use gold and silver as alternative means of payment for goods and services.
in addition to gold and silver being constitutional as a currency it is also important to note that every single unbacked, debt based, fiat currency eventually falls to a value of zero.