I think you must have run into a tv show or article about the Gnostic Gospel of Mary Magdalene. They never claimed it was written by Mary, the Blessed Virgin. However, it was not considered divinely inspired, and a couple of years ago a copy (supposedly ancient) showed up in Egypt (where the Gnostics had it) and according to this spurious "Gospel", Jesus made Mary Magdalene His chief apostle, and also the Teacher of His disciples, and Head of His Church, basically. They must have thought she had a great deal more authority than Peter!
However, the Gnostics were considered heretical, and their writings and beliefs to be not in accord with the teachings passed down by the Apostles or by St. Paul. Seems like the idea recurs periodically though. Mary, the Mother of Jesus, never wrote a Gospel, nor, as far as I know, has anyone (yet) claimed to have found such a writing, but no doubt someone will fake one up eventually! Be not disturbed. The Gospels and Scriptures approved by the Church are all we need, and were most carefully selected and determined to be faithful to the teachings of Christ and to be inspired by the Holy Spirit. We do not need to add any others.
The Gnostic beliefs, from what I have read or heard, were apparently of the opinion that those who were the most "intellectual" received inspiration directly from God, and therefore were the ones who could teach others, and no one else was able to reach their intellectual "plateau". (sort of prevented them from losing their authority, since obviously, by their own belief, no one else had the proper "mindset" and never would!)
Personally, I thank God constantly for the guiding hand of our Holy Catholic Church, or I'd have gone badly astray long ago!