Today's free book is The Boy's King Arthur by Sidney Lanier (1880). For the table of contents, check at the bottom of this post below the image.
The book is available at UFDC (I have not checked for other online sources).
Table of Contents
King Arthur
Sir Lancelot
Sir Gareth of Orkney
Sir Tristram
Sir Galahad and Sir Percival
The Death of Arthur