May 16 is her memorial and the anniversary of her canonization.
She is always shown with a dog - but don't let that fool you - she was pretty austere after her conversion, and wouldn't have squandered her affections on a pet. She treated her son fairly harshly as well. The dog belonged to her lover. He came to fetch Margaret after he was murdered, leading her to discover his body in the woods - which was the catalyst for her sudden conversion.
Discovering the corpse of her lover, Margaret understood she had been deluded, placing all of her hope in the acceptance and approval of her lover, including the status his lifestyle afforded her. Yet that security pretty much vanished with his death. She was alone, unmarried, with a child - even her father turned her away. The temptation to depend upon her own wits, to return to her old life became overwhelming. Her conversion, so unstable at first, demonstrates for us that our misfortunes are not immediately recognized for what they are - a call from God. Instead, in our panic, fear of the unknown can compromise our choices, making us all the more vulnerable to concupiscence as a means of survival.
Margaret's conversion was painful and a difficult struggle. She was tested and mistrusted by the friars who guided her, as well as townsfolk. Only after three years was she allowed to enter the Third Order of St. Francis. Her son eventually became a friar with some difficulty. I always imagine life at home with his penitent mother had to be extremely difficult as well. Margaret isn't the patron saint of the falsely accused, tramps, homeless, insane, mentally ill, for nothing.
Margaret is best known for her penitence, her mystical union with Christ, as well as her charity, caring for others less fortunate - yet she lived her reformed life under suspicion - her past reputation always followed her, and aroused gossip. Our Lord called her the Magdalene of the Franciscan order. Although it was only after her death that her conversion and penance was made known by her confessor, and the rumors and innuendo finally ceased.
St. Margaret, pray for us.