Pa traded furs for seed potatoes and seeds for garden vegetables, turnips, carrots, onions and cabbage. He also traded for a new plow. In order to plow up the tough prairie sod, Pa needed a breaking plow. The mustangs, Pet and Patty, had to work hard to pull the new plow through the thick roots of the prairie grasses. Sometimes Pa had to chop the grass with an ax before the plow could pass through.