You can read an interview with Amy Welborn about her book, De-Coding Mary Magdalene: Truth, Legends and Lies here.
IgnatiusInsight.com: What do we know about Mary Magdalene and what are our sources for our knowledge of her?
Welborn: Our primary sources for knowledge of Mary Magdalene are in the Gospels. From them, in Luke 8, we learn that Mary of Magdala (a small town on the Sea of Galilee) had been exorcised of seven demons by Jesus, and left everything behind in gratitude to follow him, along with some other women, and provide for the disciples' needs. This could be doing domestic work for them, providing funds to support the ministry, or both.
We then see Mary, in every gospel, at the Cross, then as the first to discover the Empty Tomb.
There is an enormous amount of legendary material about Mary Magdalene in both West and East. It's fascinating and rich. One of the primary strains in the West has her traveling to Provence (an idea picked up by the radical feminist author of The Woman With the Alabaster Jar, Margaret Starbird, and then turned for her own ends) and, along with Martha and Lazarus, evangelizing the area; there is even some medieval art that depicts Mary preaching and baptizing. She was a favorite subject for medieval mystery plays and, of course, art.
But what we know for sure about her is contained in the Gospels.
Amy Welborn Interview