Diana Wynne Jones has a couple others that fit your description: Seven Days of Luke, Power of Three (ordinary children, magic happens), Aunt Maria, The Ogre Downstairs (ordinary children, magical chemistry set).
You might also try Jane Langton. She wrote a series of YA books set in Concord, Massachusetts, the first (and my favorite) is The Diamond in the Window, followed by The Swing in the Summer House and others. The children are ordinary, but some of the adults are not, and none of the dreams are.
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You might also try Jane Langton. She wrote a series of YA books set in Concord, Massachusetts, the first (and my favorite) is The Diamond in the Window, followed by The Swing in the Summer House and others. The children are ordinary, but some of the adults are not, and none of the dreams are.