All my life my mom has given away what I treasured, momentos, cats, puppies. Since he was little, she has tried to buy my son. Now shes succeeding....?

Not sure of question. Sounds like giving things away a child likes and treasures would not win that child over. Is mom is giving your son "treasures" to win him over? What could be the difference in mom's eyes between now and then? Is it intentional? Is mom aware? Can anyone talk to her reasonably? Be open and kind if asking her about it. Most important is continuing a loving strong bond with your son.
Perception shift. When we perceive people loving us we act very kind if we perceive others as being hurtful we reflect the same. So try to perceive this act from your sons point of view if he is happy be supportive if your son does not want this you can set boundaries.