In addition to poor boxes, where coins were collected to help alleviate the poor, boxes were also often on display to collect alms for the souls in Purgatory. Poor boxes were the primary source of funds for the poor before governments began to try to alleviate poverty in the 19th century. The Catholic Church was and still is the single largest charitable organization in the world.
Alms for the Poor Souls, however, are intended to support the Church and the donations would help alleviate the suffering of the Poor Souls in Purgatory. While we likely are aware of the concept of praying for the Poor Souls, to help alleviate them from their debt that they owe before they are pure to enter Heaven, few Catholics are taught that we can also help the Poor Souls by also giving alms or by fasting.
Prayers (Rosary, Masses, Divine Office, etc) for the Poor Souls, fasting offered with the expressed intention to help the Poor Souls, or alms given to the poor or the Church for the intention of helping the Poor Souls are the 3 ways we can help their sufferings. We need more traditional Catholic priests teaching this truth with clarity.
How often do you pray, fast, or give alms for the Poor Souls?