Unfortunately, this isn't true:
I again urge a revision in our silver policy to reflect the status of silver as a metal for which there is an expanding industrial demand. Except for its use in coins, silver serves no useful monetary function.
In 1961, at my direction, sales of silver were suspended by the Secretary of the Treasury. As further steps, I recommend repeal of those Acts that oblige the Treasury to support the price of silver; and repeal of the special 50-percent tax on transfers of interest in silver and authorization for the Federal Reserve System to issue notes in denominations of $1, so as to make possible the gradual withdrawal of silver certificates from circulation and the use of the silver thus released for coinage purposes. I urge the Congress to take prompt action on these recommended changes.
https://archive.org/stream/EconomicR...e/n21/mode/2up
EO 11110 was, paradoxically, a tool used to eliminate Silver Certificates by authorizing additional ones during the transition period of HR 5389 (what JFK recommended, above) implementation.