The Victory Garden by Rhys Bowen

As she gets ready to turn twenty-one, Emily Bryce longs to help with the war effort. Her parents, overly concerned with their station in life, consider it beneath them to let Emily do more than visit the local hospital with her mother. After her birthday, Emily breaks away from her parents and ends up working for the Women's Land Army, harvesting crops and doing other farm work. She also falls in love with Australian pilot Robbie Kerr, which brings more of her parent's disapproval. The Victory Garden is a cozy story about Emily finding her own way amidst the turmoil of World War I.