"On April 5, 1933, Roosevelt ordered all gold coins and gold certificates in denominations of more than $100 turned in for other money. It required all persons to deliver all gold coin, gold bullion and gold certificates owned by them to the Federal Reserve by May 1 for the set price of $20.67 per ounce. By May 10, the government had taken in $300 million of gold coin and $470 million of gold certificates."
http://www.history.com/this-day-in-h...-gold-standard
That Gold coin is nearly the identical amount of Greenbacks redeemed after the Civil War. It is my belief (backed by the Congressional record) that those coins were given to the US treasury and are held in trust, by those who demand lawful money redemption.
We now have proof that those funds (by representation) are IN circulation by the Treasury accounting document and are accessed by DEMAND for lawful money per 12 USC 411.