In Thank You M'am, why is Roger unable to say what he wants to say?
In Thank You M'am by Langston Hughes, Mrs. Luella Bates Washington Jones could so easily hand Roger over to the police after he tries to steal her purse. Instead, she recognizes a need in him for some wise, adult intervention because his actions reveal a misdirected boy in need of guidance. She spontaneously decides that she can not only teach him a lesson but also show Roger that he does have other choices in life and petty crime will not serve him well. Mrs. Jones relates to Roger and remembers a time when she "wanted things I could not get." She is not a wealthy woman and she tries to show Roger that there are other ways to get what you want, even suggesting that he could have asked her, which has Roger bemused. Her actions do reveal to him that not everyone mistrusts others and that everyone deserves a second chance.
At first, Roger worries that Mrs. Jones is going to take him to the police, and even after she takes him into her home, he considers running away but something stops him. He does not expect her to trust him and when she does, he feels a need to offer some token of gratitude by offering to go to the shop for her. The last thing he expects is that Mrs. Jones will give him a decent meal and even give him enough money for the shoes.
Mrs. Jones's actions have such an impact on Roger that he knows that he owes her far more than a simple thank you but he is overwhelmed by her generosity and by the fact that she wants nothing in return except that he should "behave yourself." There is potential to interpret a double meaning from Langston Hughes's use of the word large as Mrs. Jones's "large" personality and compassion, for Roger, have had a big influence (hopefully) on his life and his future, rendering him almost speechless.