If they are her toys why does he have to pick them up actually if you walk in his shoes he may have a point ,it could be some child/parent interaction that needs adjusting, I have actually seen this scenario for myself where the older child has to do things and give up things for the younger one and it does have the effect of making them jealous , next time you want toys picking up why not all join in doing it so he feels as if its just not him.,that is being fair to them both.At 3 year old there are probably a few things she can do for herself , and helping clear up is definatly one of them.Focus on his positive side and praise him when you see him doing something right.