A social media video shows the woman admitting to using the slur and then appearing to double down and raising a middle finger to a man who confronted her.
Till, 14, was killed in 1955 by two white men who were acquitted by an all-white jury but later told a reporter that they kidnapped and murdered the boy.
The provisions in a new Mississippi policy would bar discussions of "divisive concepts" related to race, sex, gender identity, sexual orientation and national origin in schools.