Do begging-letters ever result in gifts?

An acquaintance of mine who is a bit short on money, jokingly, told me recently that she would write a begging-letter to Mr. Gates, with the question if he could send $50,000.
I wished her good luck and told her that he and all the other billionaires probably get bags full of them on a daily basis and that it must contain that a dramatic message or be that original to have the littlest chance if at all that you’ll be gifted.
Does anyone of you know/heard of cases in which it resulted in cash for the writer?
How would you compose a letter like that, or what original message would you attach given the imaginary case that you would feel the need to do so?