There is a conspiracy theory that claims that JFK was on a mission to re-introduce silver money and end the Fed, but this has been debunked by none other than G. Edward Griffin, a bona fide conspiracy theorist who says that the fed needs to destroy the dollar to usher in a cashless system.

He was open to this JFK theory because he wouldn't put it past the fed to kill him over this, but he found the theory to be false upon examination.

Fascinating video where he describes his research here: