The Princess with the Ball Is Pregnant with a Rare Treasure

The heroine once traveled to the Zuo Xiangfu of the Donglin Kingdom and became the "unmarried and pregnant" eldest daughter of the Wen Xiangfu. She was going to marry the ill male protagonist in a few days. The heroine accidentally gets the rare mustard seed, and relies on it to teach the Xie family who bullied the original owner, marry into the prince's palace, and make a three-part agreement with the hero, and from then on live a life like a rice bug.