Warren and his next-door neighbor Bill, who's an illustrator and a gardener, are best friends. The little boy is welcomed as Bill's garden helper—they check out the ``garden zoo'' (``Larkspur rabbits....Monkey faces in the pansies...''), weed, transplant, make a game of escaping from the sprinkler, and tell stories about ``snapping dragons.'' After Warren moves, he sends Bill an imaginative picture of a dragon in a garden—which gives Bill an idea for a new storybook and also elicits a present of seeds from his garden so that Warren and Dad can start their own. The simple, adroitly crafted story is agreeably extended in Bjîrkman's sun-dappled watercolors, where Warren's family happens to be white and Bill is an African American whose garden is a luxuriant mass of flowers. A delightfully fresh variant of the best-friend-moves-away theme. (Picture book. 4-8)