The Children of Green Knowe...L. M. Boston...Harcourt, Brace, and Company
Treasure of Green Knowe...L. M. Boston...Harcourt, Brace, & World, Inc.
The River at Green Knowe...L. M. Boston...Harcourt, Brace, & World, Inc.
A Stranger at Green Knowe...L. M. Boston...Voyager/Harcourt, Brace, Jovanovich
An Enemy at Green Knowe...L. M. Boston...Harcourt, Brace, & World, Inc.
The Boggart...Susan Cooper...Aladdin Paperbacks/Simon & Schuster
The Boggart and the Monster...Susan Cooper...Aladdin Paperbacks/Simon & Schuster
Tom's Midnight Garden...Phillipa Pearce...Harper Trophy/HarperCollins
The Foundling and Other Tales of Prydain...Lloyd Alexander...Dell Yearling
The Wizard in the Tree...Lloyd Alexander...Dell Yearling
Bridge To Terabithia...Katherine Paterson...Avon/Camelot
The Green Knowe books were published in the period spanning 1954-1964. They deal with the adventures of various children in a magical old house (called Green Knowe). The book I first read in middle school was An Enemy at Green Knowe; I was looking for magic books like Bed-knob and Broomstick, which had had a deep influence on me, and it seemed to fit the bill. I never saw the series again till years later, when I was able to get most of the volumes at a San Antonio library sale (all except for Stranger; I got that when the series was re-printed in the wake of Harry Potter).
Middle school was also where I read The Wizard in the Tree, by Lloyd Alexander (who of course is more famous for his Prydain Chronicles). I read The Sword in the Stone, and Howard Pyle's King Arthur and the Knights of the Round Table, and an adaptation of Beowulf, and I peeked into The Lion, the Witch, and the Wardrobe (and decided at the time that it wasn't for me!). And I first read The Hobbit, and then all chocks were off.
Susan Cooper's Boggart books are the latest published on this list, from '93 and '95. These books are good reads, but her The Dark Is Rising series is great; in those books Cooper's conception and writing talent are superior to J. K. Rowling's by far. It is a pity that so many people will only know them through the awful movie The Seeker. Tom's Midnight Garden was more fortunate in its' movie adaptation; it was blessed with the considerable talents of Joan Plowright. Bridge To Terabithia is of course not a fantasy: it is about fantasy, however, and its power to affect real life.