The first and last lines, “I, too, sing America.” seem like a reminder that black people are in fact visible, and people who matter just like their fellow, privileged Americans. In line 3, the “they” could possibly refer to the white people that the speaker is working for/serving, or the white people who run the hotel or restaurant. During these times, whites and blacks could not eat in the same areas. Blacks were treated like second-class citizens, and sometimes still are, by the way. In a more general sense, “they” could refer to all white people in America to see how radiant and worthy that the speaker and people like him are. Moving onto line 4, “when company comes” relates to when white people had fellow white guests over, black servants