The Loyola Kids Book of Saints by Amy Welborn contains stories about holy men and women for children, retold in a way to help the reader understand how the saints' journey and struggles might be similar to their own.
From the old Catholic Encyclopedia:
St. Monica was buried at Ostia, and at first seems to have been almost forgotten, though her body was removed during the sixth century to a hidden crypt in the church of St. Aureus. About the thirteenth century, however, the cult of St. Monica began to spread and a feast in her honour was kept on 4 May. In 1430 Martin V ordered the relics to be brought to Rome. Many miracles occurred on the way, and the cultus of St. Monica was definitely established. Later the Archbishop of Rouen, Cardinal d'Estouteville, built a church at Rome in honour of St. Augustine and deposited the relics of St. Monica in a chapel to the left of the high altar. The Office of St. Monica however does not seem to have found a place in the Roman Breviary before the sixteenth century.