http://gutenberg.net.au/ebooks02/0200551h.zip
http://gutenberg.net.au/ebooks02/0200561h.zip
Mark Twain (1835-1910)
Except for some posthumous publications, like the one below, all of Mark Twain's work is in the public domain in the US. Here is a complete list of available online works, including his "Chapters from My Autobiography", which is public domain everywhere.