Her image and her name
Depictions of her image
No picture has preserved for us the true likeness of Mary. The Byzantine representations, said to be painted by St. Luke, belong only to the sixth century, and reproduce a conventional type. There are twenty-seven copies in existence, ten of which are in Rome.  Even St. Augustine expresses the opinion that the real external appearance of Mary is unknown to us, and that in this regard we know and believe nothing.  The earliest picture of Mary is that found in the cemetery of Priscilla; it represents the Virgin as if about to nurse the Infant Jesus, and near her is the image of a prophet, Isaias or perhaps Micheas. The picture belongs to the beginning of the second century, and compares favourably with the works of art found in Pompeii. From the third century we possess pictures of Our Lady present at the adoration of the Magi; they are found in the cemeteries of Domitilla and Calixtus. Pictures belonging to the fourth century are found in the cemetery of Saints Peter and Marcellinus; in one of these she appears with her head uncovered, in another with her arms half extended as if in supplication, and with the Infant standing before her. On the graves of the early Christians, the saints figured as intercessors for their souls, and among these saints Mary always held the place of honour. Besides the paintings on the walls and on the sarcophagi, the Catacombs furnish also pictures of Mary painted on gilt glass disks and sealed up by means of another glass disk welded to the former.  Generally these pictures belong to the third or fourth century. Quite frequently the legend MARIA or MARA accompanies these pictures.
Use of her name
Towards the end of the fourth century, the name Mary becomes rather frequent among Christians; this serves as another sign of the veneration they had for the Mother of God. 
No one will suspect the early Christians of idolatry, as if they had paid supreme worship to Mary's pictures or name; but how are we to explain the phenomena enumerated, unless we suppose that the early Christians venerated Mary in a special way? 
Nor can this veneration be said to be a corruption introduced in later times. It has been seen that the earliest picture dates from the beginning of the second century, so that within the first fifty years after the death of St. John the veneration of Mary is proved to have flourished in the Church of Rome.
For the attitude of the Churches of Asia Minor and of Lyons we may appeal to the words of St. Irenaeus, a pupil of St. John's disciple Polycarp ; he calls Mary our most eminent advocate. St. Ignatius of Antioch, part of whose life reached back into apostolic times, wrote to the Ephesians (c. 18-19) in such a way as to connect the mysteries of Our Lord's life more closely with those of the Virgin Mary. For instance, the virginity of Mary, and her childbirth, are enumerated with Christ's death, as forming three mysteries unknown to the devil. The sub-apostolic author of the Epistle to Diognetus, writing to a pagan inquirer concerning the Christian mysteries, describes Mary as the great antithesis of Eve, and this idea of Our Lady occurs repeatedly in other writers even before the Council of Ephesus. We have repeatedly appealed to the words of St. Justin and Tertullian, both of whom wrote before the end of the second century.
As it is admitted that the praises of Mary grow with the growth of the Christian community, we may conclude in brief that the veneration of and devotion to Mary began even in the time of the Apostles.
(Taken from the Catholic Encyclopedia)