I am the cheese.
Adam thinks this to himself in the final first person narrative section (Section 10), after reciting the song, "The Farmer in the Dell." Three out of four lines in each verse of the song repeat some "taking" action, such as "The farmer takes a wife" or "The wife takes a child." The final verse of the ditty is "The cheese stands alone," and this is how Adam feels—he is alone, without any parents or even his own identity. Cormier has solved the mystery of Adam identity, however, Adam is unable to handle the truth of his past. He sends himself back to having no identity, he is simply alone and he is simply "the cheese." The quote answers the mystery of the novel's title, and encapsulates Adam's struggle with his painful situation.