Crossley-Holland, K: Arthur: The Seeing Stone: Book 1

The year is 1199, the place the Welsh Marches. Young Arthur de Caldicot practises his tilting and archery, learns to be a dutiful page to his father, and waits impatiently to grow up and become a knight. One day his father’s friend Merlin gives him a shining black stone. When Arthur starts to see stories in the stone, his life quickly becomes entwined with that of his namesake, the boy who pulls the sword from the stone.