The talented illustrator of last year's Frog Went A 'Courtin' now turns her attention to a famous nursery rhyme. The familiar first verse is repeated, but subsequent verses have been completely rewritten or repositioned to fit in with a complicated design in which characters from other nursery rhymes are integrated into pageant-like double-page spreads. The nonsense of the verses is preserved, but the rhymes, uneven in their success, are mostly Conover's. Simple Simon has a pumpkin head and exists in a landscape that includes pandas in Chinese costumes, bears in medieval garb, a polar bear who dons a suit from Lapland, and several turnips with faces, arms, and legs. A circus with a camel and an elephant appears in the middle of the action, and it begins to snow. Simple Simon unsuccessfully attempts to buy a pie, pick purple plums from thistles, ride a spotted cow, and so forth. Characters from ""Little Jack Homer,"" ""The Queen of Hearts"" and 14 other nursery rhymes are scattered throughout. All of this is pictured against backgrounds that vary from dull gold to bluish purple, the figures crisply outlined in Conover's usual style. In all: entertaining and charming, if hardly filling a real need, with its antically absorbing puzzle-pictures making up for whatever defects occur in Conover's verse.