Chuanyue Meiren Zai Zuo Yao

When a modern girl wakes up after falling into a lake, she realizes she has traveled into the novel she was reading and became Wu Yulin, the princess consort of the lord of East Lin City, Song Wei. After Yulin discovers that the lord's thumb ring is the key to coming back to the real world, she tries her best to obtain it. But before she succeeds, the lord seems to have fallen for her.
(Source: WebComics)