Were George Washington and Thomas Jefferson—two of the founding fathers of the United States and its first and third presidents—secretly 420 friendly? Well, for starters, the word "marijuana" and its various nicknames weren't really popularized until the late 1800s, so if George and Thomas passed a bowl together, they definitely didn't call it weed.
Hemp itself was a very common cash crop back then, going all the way back to England's original occupation of the Americas. No surprises there, considering how useful it is: You can use hemp to make rope and canvas for nautical use, cloth for fabric to sew clothes, and even pulp for paper. In fact, it's rumored that early drafts of the Constitution of the United States of America may have been written on paper made from hemp—though its final draft was written on parchment.
George Washington surely grew hemp at Mount Vernon, both to sell as a crop and to use in the repair of large fishing nets utilized in a fishing operation that he operated along the Potomac River. By the middle of the 18th century, Washington theorized that hemp might become more popular than tobacco—though, sadly, this prediction would never come true in the United States.
One of the greatest sources for the myth that Thomas Jefferson enjoyed a regular toke is this quote, attributed to him: "Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see."
Jefferson's own hemp production was very impressive: He chose to raise hemp at Monticello instead of tobacco, perhaps suspecting, as Washington did, that it would outpace tobacco as a cash crop sooner or later. By 1815, Monticello was processing upwards of 2,000 yards of cloth per year, purely made out of hemp. Unfortunately, he was later forced to cease production, as growing hemp was particularly labor intensive at the time.
While that quote has been circulated far and wide, and it's known that Jefferson did grow hemp, there's no evidence to suggest that Jefferson ever actually spoke those words! There's also no proof that Jefferson was a smoker of any sort, whether it be hemp or tobacco.
The quote itself is considered to be an internet hoax, first appearing in 2008, and then receiving print circulation in 2013. It's been printed in physical papers like Detroit Free Press, as well as newspapers in British Columbia and India, and has also been spread across the internet in image macro form for years now. But, according to American University School of Communication professor W. Joseph Campbell's book about myths in American journalism, it is "fake news," despite being parroted by pro-legalization presidential candidate Gary Johnson in 2012.
So it seems unlikely that Washington or Jefferson ever toked up at the privacy of their own estates... but we all know had the practice been more popular at the time, George and Thomas—ever fans of personal liberty—could probably have put us all to shame.