This took place on the Fourth Sunday of Lent. The epistle assigned to that Mass described the heavenly Jerusalem as "our mother." Knowing that catechumens were preparing for entry into the Church at Easter, Christians remembered and gave thanks for their own baptism, and visited their "Mother Church" (the church where they were baptized).
This eventually led to the custom of people in England honoring their own mothers on that day.
- Little Black Book, Diocese of Saginaw