This was in the Youth's Companion from November 27, 1863
Curiosities of the Mail
A letter from Washington contains the following:
Among the articles sent to the soldiers through the mails, and which broke through their envelopes, and were picked up in the Washington Post Office, is a live terrapin. The animal was found two or three days since in good health. A soldier had sent it to a friend. Yesterday, a still more singular thing came to light in the same office - a human finger - a soldier having lost his finger by amputation, first dried it and then sent it to a friend in England! As he enclosed it in a newspaper, instead of paying letter postage on it, the document was stopped here.