Whenever I walked past this store, Aida’s, I understood that they sold ceremonial outfits for baptisms and communion, but I never “got” the presentation part. I took a photo to remind myself, then looked online. I found this article on Mexican traditions that explains it:
Other religious traditions focus on rites of passage such as baptism, the presentation of children to church (presentación de los niños), first communion, and quinceañeras. When children turn three they are sometimes presented to the church because that was the age when the Virgin Mary was presented to the temple for the first time. Some informants mentioned that the ceremony marked the passage of a baby to that of a child. In addition, Father Pedro said that parents will bring children anywhere from a few months to 5 years of age to take part in the ceremony. In return for the blessing parents will present the priest with wine, bread, fruit, or other items that the church can use. The particular ceremony differs from place to place in Mexico, but based on conversations with a number of migrants, Father Pedro believes that the tradition is mainly practiced in Louisiana by workers from the state of Guanajuato. Following the blessing, a party with food and music, is provided for the celebrants.
The web site has to do with Louisiana traditions, that’s why Louisiana is mentioned, but I’m guessing that this is a tradition with Mexicans everywhere?