A scholar discovered one by chance. "I don't want to belittle his participation or his role because it really is quite important. This is one of the things we had not published," explained General Editor of the Mark Twain Project Robert Hirst.
Twain told bedtime stories to his daughters, but they were never for the masses and almost never written down.
"As far as I know -- it's the only one we have," said Hirst, referring to one story in particular. "We don't know what the other stories were like or what they said."
"Oleomargerine" is an unfinished story, but in it the scholar found a clue.
There's a note written on the manuscript that reads, "Karoo hostess ain't she -- Susie."
Susie is one of Twain's daughters. This proves "Oleomargerine" was one of Twain's bedtime stories.
VIDEO: Full interview with Mark Twain Scholar Robert Hirst
"A lot of people look through this and didn't tumble to that. And I've transcribed it -- and I didn't tumble to that," said Hirst.
The manuscript became the inspiration for a new children's book: "The Purlonging of Prince Oleomargerine."
While a new author will bring Twain to life again -- scholars say he probably wouldn't like it.
"We have plenty of evidence that he did not like people tinkering with his stuff," Hirst told ABC7 News.
You can access the Twain archives at Berkeley for your own literary inspiration.
Click here for more information on the U.C. Berkeley Mark Twain Project Archives.