I think I must have read this book at school when I was about the same age as Z. I remembered the passage where Epaminondas arrives home with butter streaming out of his hat.
"Law's sake! Epaminondas, what you got in your hat?"
"Butter, Mammy," said Epaminondas; "Auntie gave it to me."
"Butter!" said his Mammy.
"Epaminondas, you ain't got the sense you was born with! Don't you know that's no way to carry butter?
Amazon suggests buying Epaminondas along with "The Story of Little Black Sambo" which I also remember reading at school, before it was banned.
But then I lived on an island where there were no black people and the Pakistanis who came twice a year to sell clothes from the back of a van were known as "the darkies".