George Washington
Like the cherry tree, it's a myth that George Washington was once offered a king's crown.
However he did resign his military commission, and refused a third term as president. When King George III was told by his American painter Benjamin West that Washington was going to resign and return to his farm, the king reportedly said, "If he does that, he will be the greatest man in the world."
Unfortunately, most modern politicians, offered such a crown, would probably jam it so firmly onto their own heads that it would need to be cut off to remove it.