Folk magic and folk morals but not, strictly speaking, folk tale. From a German author, recently deceased, comes an assortment of wish-fulfilling pots, forbidden rooms and ugly but benevolent sprites in a geography that ranges from Eternal Spring to Golden Acres. ""The Adventures of Jack Grumbles"" runs the gamut: after a journey through the realms of King Pleasure, King Miserable, King Lazybones and King Busybody, Jack doesn't grumble any more--he's glad to be home. Some are more casual, and the long episodic ""The Enchanted Garden"" could be the outline for an operetta. What's amusing are characters who confound expectations: the king so poor his ssubjects let him win at cards, the bookseller who can't bear to part with a single volume. An agreeable if not a distinctive collection, then, with one sticking point--it's just not worth the money (most of which must have gone into the heavy stock that makes 200 pages into a tome ). The illustrations look attractive until you look closely and see that they're vacuous.