President Abraham Lincoln received a gift of a cane, but he couldn't make out the signature on the letter accompanying the gift.
So he cut out that signature and pasted it onto his thank you note to use as the salutation.
I relate so much to Lincoln's anxious brain in July 1864 looping through: "Need to finish that proclamation for 500,000 more soldiers. Sherman needs supplies. Can I pardon this deserter? How in hell am I going to send this thank you letter?"