Posthumously published, this ingenuous tale by the creator of Corduroy introduces another endearing, though not likely as enduring, animal character. Gregory Groundhog always feels braver when his best pal, his shadow, accompanies him. On the day before Groundhog Day, Gregory suggests that he and Shadow go find something to eat. ""Sure... I'm right behind you,"" quips his amorphous companion, whom Gregory inadvertently leaves outdoors when he returns to his burrow. After the two are reunited, the groundhog faces another dilemma: He doesn't want to be separated from his friend again, yet he knows that his appearance with his shadow on the following morning will make the local farmers unhappy, since this augurs six more weeks of winter. Not surprisingly, Gregory devises a simple solution to this quandary that pleases all involved. Less engaging than Freeman's light yet satisfying narrative are his wispy, sketchy pictures--a number of which seem unfinished. Still, the whimsical notion of a groundhog's all-important shadow taking on a life of its own will pique readers' imaginations, and the antics of these two earnest buddies will bring smiles to young faces. Ages 2-6. (Dec.) FYI: A portion of the author royalties from this title will go to the Don and Lydia Freeman Research Fund to support psychological research concerning children afflicted with cancer.