Rings of Passage: A time travel novel with Richard III (Paperback) by Karla Tipton

Heroine Anise Wynford stumbles down the porch steps of her farmhouse in Massachusetts and into the nightmare of a raging battlefield of armor and sword fighting. When she later awakens in a medieval forest in the presence of a gallant white knight, their connection is immediate. Concerned for her safety, the knight carries her to his castle. Her knight turns out to be King Richard III, the villain of Shakespeare's most famous play. The truth dawns that she has been transported through time by a magic ring. As Anise navigates the complex rules of politics and etiquette in the king's court, she falls in love with Richard and he with her. But Anise knows Richard is destined to die in the Battle of Bosworth Field. If Anise chooses to save his life, she will alter the course of history.