Arthur: The Seeing Stone by Kevin Crossley-Holland
I had read Gatty's Tale by the same author so I was interested in more. This story is really about life in the middle ages and includes many of the legends of King Arthur. It is the story of a boy named Arthur and a man called Merlin who gives him a magic stone in which he can see things happening.Arthur at the Crossing Places by Kevin Crossley-Holland, the second book in a series of three.
More about Arthur, what he sees in his stone, his desire to become a knight one day and the girls he likes. These books have a great deal of interesting details about life in those days.