suggested by members of the SCA-Librarians mailing list.
The Knight and the Dragon by Tomie DePaola
"It is a lovely little picture book with a happy ending brought about by the castle librarian!"
-- Recommended by Branwen
Also the "duchess" (or maybe "baroness"? We seem to have weeded them out of our catalog) books by Krahl, from the early seventies, picture books about a duke and duchess with lots of daughters. Pleasant little stories in rhyme.
-- Recommended by Branwen
Adventures of Rinaldo. by Isabella Holt.. With pictures by Erik Blegvad.[1st ed.] Boston, Little, Brown  142 p. illus. 22 cm.
A knight returning from the "wars" to a dilapidated castle..
The Earthly Knight. by Janet McNaughton. HarperCollins, 2004.
Retelling of Tam Lin set in 12th century Scotland.
-- Recomended by Katerina
Pearl in the Egg: a tale of the thirteenth century by Dorothy Van Woerkom. HarperCollins Children's Books.1980.
Tale of a serf girl who runs away
with a troupe of traveling players to stay free a year and a day.
The author at the back cites some references to Maltilda (I think it's Makejoy) who was a female storyteller listed in the pay rolls of a royal wedding.
- recommended by Cassandra of Wyndhaven
A Proud Taste for Scarlet and Miniver. by E.L.Konigsburg. Simon & Schuster Children's. 1977.
One of my absolute favorite fictional treatments. A fictionalized version of the life of Eleanor of Acquitane. In the fantasy sequences around the story, Eleanor of Acquitaine is waiting in Heaven for her second husband, Henry II of England, to be allowed out of Purgatory. She and various close acquaintances from her past pass the time by telling the story of her life. Humorous, pungent, and capturing the flavor of Eleanor's life. Interesting side comments on William the Marshall, the building of cathedrals, Norman run, Thomas a Becket, taxes and so forth in the Middle Ages:
"Her name is Eleanor, and she is well educated."
"Does that mean, dear Abbot, that she embroiders beautifully and knows the proper order in which to hand armor to a knight?"
"Yes, it does." I smiled. "But in this case, fortunately, it also means something more. She can read Latin, and I am told that she knows a great deal of music and poetry. She comes by those talents naturally; her grandfather was a poet as well as a knight."
- recommended by Jadwiga
Other Reviews: The Green Man Review: http://www.greenmanreview.com/a.proud.taste.htm
ALA's Book Links: http://www.ala.org/ala/booklinksbucket/eleanoraquitaine.htm
Reading Guide: http://www.forestridge.org/faculty/fierce/medieval/scarlet/scarletguide.htm
The Ramsay Scallop by Frances Temple.
"A terrific book for tenth grade and up. A young girl and the disillusioned crusade-veteran she's espoused to are sent on pilgrimage by their parish priest to bring healing to their village. The story manages to bring in a vast number of disparate medieval themes, is solid in its history, and is a great "read". Come to think of it, I think I'll read it again when I get home from vacation."
-- Recommended by Branwen.