On Saturday, after returning home from the temple, we walked to the house a few doors away to buy cheese and noticed a wire cross made of flowers attached to the front gate. We asked why she had flowers and she said she didn't really know why they did it but that’s what you do when it is the “dia de la cruz” or “day of the cross” on May 3. After we left her house we began to notice several crosses with flowers on the front of the neighbors' gates. We ring the bell on the gate when we are here to buy cheese.
Gracias! a Wikipedia for the following information about May 3, "Fiesta de las Cruces":
"The legend is that Emperor Constantine I, in the sixth year of his reign, confronted the barbarians on the banks of the Danube, in a battle where victory was believed to be impossible because of the great size of the enemy army. One night, Constantine had a vision of a cross in the sky, and by it the words "In hoc signo vincis" (With this sign, you shall be victorious). The emperor had a cross made and put it at the front of his army, which won an easy victory over the enemy multitude.
On returning to the city and learning the significance of the cross, Constantine was baptized as a Christian and gave orders to construct Christian churches. He sent his mother, Saint Helena, to Jerusalem in search of the True Cross, the cross on which Jesus died. Once there, Helena summoned the wisest priests to aid in her attempt to find the cross. On Calvary Hill, traditionally considered the site of Jesus's crucifixion, she found three bloody logs hidden. In order to discover which was the True Cross, she placed the logs one by one over sick people, and even dead people, who were cured or resuscitated at the touch of the True Cross. The veneration of the True Cross, and the use of pieces of the True Cross as relics, begins at this time. Santa Helena died praying for all believers in Christ to celebrate the commemoration of the day the Cross was found."