From Catholic News Agency:
St. Joachim and St. Anne were Jesus' grandparents and Mother Mary's parents. The Gospels don't tell us anything about this couple. Still, devotion to the couple, especially St. Anne, is great and dates back to the sixth century in the Church of Constantinople and the eighth century in Rome. It increased even more in the 13th and 14th centuries.
The only writings that exist about St. Joachim and St. Anne are found in the Protogospel of John, which was not included in the canon of Scripture.