Greg smiles at the end of “The Treasure of Lemon Brown” because his treasure is the love of his father expressed in the form of lectures telling him to work to be better. His treasure is stability and a home, even if he lets school work slide in favor of sports, just as Lemon Brown’s music and honor are his treasure.
This central theme of Walter Dean Myers’s short story is determining what is worth fighting for in life. Although at the end of the story, Greg is still unwilling to buckle down to improve his math grade so that he can try out for a basketball team, he knows that he can do better. His father’s lectures remind him that the older he gets, the more responsibility he’s expected to take for himself and his actions. The story is also in part about self-discipline, namely Greg’s willingness to work to play basketball versus his father’s commitment to hard work. Greg and his father clash over practicalities.
Evidence that Greg intends to work harder in school comes in the form of his willingness to defend a stranger. When thugs threaten Lemon Brown, it doesn’t occur to Greg not to try to help, even though he’s frightened and doesn’t know what to do. Furthermore, while he’s wary at first of a stranger, he’s still courteous and attentive, just as he is during his father’s lectures. Even though he has not yet learned self-discipline, Greg is learning about respect, dreams and honor.