"You had better shove this in the stove," Mark Twain wrote to his brother in 1865, "for I don't want any absurd 'literary remains' and 'unpublished letters of Mark Twain' published after I am planted." Despite this, a collection of previously unpublished stories and essays by the great American writer are due out this April, almost 99 years after his death.

The title of the collection, Who is Mark Twain? is a reference to Twain's essay Frank Fuller and My First New York Lecture, included in the book. In the essay, Twain relates how – anxious that no one would attend – he plastered New York with advertisements to promote his talk. He later observed two men looking at the ads. One asked, "Who is Mark Twain?", to which the other responded: "God knows – I don't."

Another essay, Jane Austen, sees Twain – born Samuel Clemens in 1835 – ask if Austen's goal is to "make the reader detest her people up to the middle of the book and like them in the rest of the chapters", while the previously unpublished short story The Undertaker's Tale is a tongue-in-cheek piece about the funeral industry.

HarperStudio, the publisher of the 24-piece collection put together by Robert Hirst, general editor of the Mark Twain Project at the University of California, said that Twain left behind the largest collection of personal papers created by any 19th-century American author. "The pieces themselves are wonderfully, hilariously contemporary, and deserve as wide an audience as possible," said publisher Bob Miller.