Why is cassie unhappy with where big Ma is selling her good? Which particular event ruin cassie's day in Strawberry? Why dosen't Big Ma want cassie to tell Uncle Hammer about her day in Strawberry?

Cassie is unhappy because Big Ma parked her wagon in a place where it would be hard for people to see her selling her goods.

Mr. Barnett was rude to Cassie and he ruined her day.

Big Ma doesn't want Cassie to tell Uncle Hammer about Mr. Barnett because she doesn't want him to retaliate.