What does Cassie learn about her family from Big Ma in Roll of Thunder, Hear My Cry by Mildred D. Taylor?

Cassie learns from Big Ma how Mr. Paul Edward, her grandfather and former slave, acquired the 400 acres of land in Spokane County, Mississippi, that once belonged to the Grangers.

One day the children see Mr. Harlan Granger's expensive car pulling away from their dusty driveway. "Big Ma, what was Mr. Granger doing here?" Stacey asks her. Big Ma replies that he has just been "worrying" her about this land again. She explains that during Reconstruction the Grangers had to sell some of their land to Yankees in order to pay the taxes on the rest. The man who bought the land, Mr. Hollenbeck, sold him 200 acres. Later on, Mr. Hollenbeck offered to sell another 200 acres back to the Grangers at a lesser price than his purchase. But, "old Filmore Granger," who was "tight with a penny" refused to buy it.

Later, a Mr. Charles Jamison from Vicksburg purchased it. However, he was not good at farming, so after he graduated from law school in the North, he started practicing law there. After he died, his son Wade sold the 200 acres to Paul Edward. In this way, a total of 400 acres was acquired by Cassie's grandfather and Big Ma. Together they worked the land, and their sons did, also, when they were older. But, Mr. Granger was "always talkin' bout buyin' it." Grunting angrily, Big Ma tells Cassie, "He don't know nothin' 'bout me or this land, he think I'm gonna sell!"

Owning the land is something that gives the Logans advantages over their neighbors who have to be sharecroppers and make only a percentage of the profits on the land. Also, the owners take advantage of these farmers, charging high prices in their stores and giving them lower percentages than they should.