Sitting Down To Eat ($15.95; Sept. 1996; 32 pp.; 0-87483-460- 0): A song becomes a cumulative rhyming story about a child sitting down to eat, repeatedly interrupted by knocks at the door and animals clamoring to join in. ``If I've got enough for me, yes, that's true./If I've got enough for me,/I've got enough for you./Come on in!'' The rhymes maintain a strong beat; children will love shouting out refrains, as well as the ``BOOM'' that brings the house down when one last visitor is admitted. With Harvill's frenetic cut-paper collages, this is playful and lively. (Picture book. 4-7)