Question: Which American author wrote both The Idylls of the Queen, and the "Frostflower and Thorn" series?

Context paragraphs:
Corduroy Mansions: Corduroy Mansions is the first online novel by Alexander McCall Smith, author of the The No. 1 Ladies' Detective Agency series.  In the first series, the author wrote a chapter a day, starting on 15 Sep 2008, the series running for 20 weeks and totalling 100 episodes.  The daily chapters, read by Andrew Sachs were also available as an audio download.

The Idylls of the Queen: The Idylls of the Queen: A Tale of Queen Guenevere is a 1982 fantasy mystery novel set in the framework of the King Arthur myths written by American author Phyllis Ann Karr.  It was first published in paperback by Ace Books in June 1982, and reprinted by Berkley Books in 1985.  A trade paperback edition was published by Wildside Press in 1999.  The novel's title is inspired by Alfred, Lord Tennyson's Arthurian poetry collection "Idylls of the King".

The Mugger (novel): The Mugger is a (1956) novel by Ed McBain, the second in his 87th Precinct series.  It was adapted for a film of the same name in 1958.  In 2002 the author wrote an introduction to this and to his earlier novel "Cop Hater" when both were published in an omnibus edition.

A Conspiracy of Friends: A Conspiracy of Friends is the third online novel by Alexander McCall Smith, author of the The No. 1 Ladies' Detective Agency series.  In the first series, the author wrote a chapter a day, starting from 15 September 2008, and the series ran for 20 weeks, totalling 100 episodes.  The daily chapters, read by Andrew Sachs, were also available as an audio download.

Myōjin Yahiko: Myōjin Yahiko (明神 弥彦 ) , known as Yahiko Myojin in the Media Blasters English-language dub and Yoshi Myojin in the English Sony "Samurai X" dub, is a fictional character from the "Rurouni Kenshin" manga and anime series authored by Nobuhiro Watsuki.  The character of Yahiko is based on the author's childhood experiences practicing kendo; since Watsuki's experienced frustration during kendo classes, the author wrote Yahiko as experiencing frustration with his kendo skills.  Watsuki liked Yahiko, and while writing the manga, he began to develop the character so that readers would enjoy him.

The Dog Who Came in from the Cold: The Dog Who Came in from the Cold is the second online novel by Alexander McCall Smith, author of the The No. 1 Ladies' Detective Agency series.  In the first series, the author wrote a chapter a day, starting on 15 Sep 2008, the series running for 20 weeks and totalling 100 episodes.  The daily chapters, read by Andrew Sachs were also available as an audio download.

Phyllis Ann Karr: Phyllis Ann Karr (born July 25, 1944) is an American author of fantasy, romances, mysteries, and non-fiction.  She is best known for her "Frostflower and Thorn" series and Matter of Britain works.

Miracles from Heaven: Miracles from Heaven: A Little Girl, Her Journey to Heaven, and Her Amazing Story of Healing is a memoir written by an American author Christy Beam, released on April 14, 2015.  The author wrote the book about her own sick daughter Annabel Beam.

Sin Pit: Sin Pit is a crime novel by American journalist Paul S. Meskil (Jul 2, 1923–Oct 11, 2005), published by Lion Books in 1954.  It is one of those rare paperback originals that has achieved cult status through a combination of circumstances, including the fact the author wrote only one work of crime fiction, the initial print run was relatively low for paperbacks at the time, the book had only one print run by the original publisher (Lion Books) and, finally, found an audience years later among collectors of 1950s paperback crime novels.  Sin Pit shares all the above circumstances with another paperback crime novel published a year earlier, in 1953, that similarly achieved cult status — Black Wings Has My Angel by Elliott Chaze, published by Fawcett Gold Medal.  Both authors were respected journalists their entire lives and wrote only a single crime novel that was never republished until years later, only after gaining an audience among aficionados of pulp fiction.

Room For Love: Room For Love is a chick lit novel by American author Andrea Meyer.  The book was inspired by an article the author wrote for the "New York Post" and brings together two New York City obsessions: love and real estate.

Supporting paragraphs: The Idylls of the Queen Phyllis Ann Karr
Answer: Phyllis Ann Karr