There's a fragment in Cassius Dio's History of Rome (Book 68, p. 375) in which the Dacians send a message by a large mushroom, of which I was taught about back in 5th grade. I am quoting the English translation under:
"When Trajan in his campaign against the Dacians had drawn near Tapae, where the barbarians were encamped, a large mushroom was brought to him on which was written in Latin characters a message to the effect that the Buri and other allies advised Trajan to turn back and keep the peace.
I always found the idea of writing Latin on a giant mushroom both amuzing and disconcerting.
So, /r/AskHistorians, how common was the use of such organic means throughout history, when it came to actually writing on them? Do we know of any other occurance of mushrooms in particular?
LE: typos; the title is still crappy...
I don't know anything about mushrooms, but we have hundreds of birch bark manuscripts from medieval Novgorod, used as a cheap writing surface in a time without paper.
They were also used in India but I don't know enough about them.
I recently did research on this particular topic. Let me know if you're still interested and I'll be happy to share my findings. :)