What right can a teacher possibly have for not letting the parent take the bag in the first place? This is private property and not her decision to throw it away. This is the whole crux of the matter and it seems to have been left out of the report on purpose. It is the key to the whole matter. Why stop mom from taking it? Let her have the bag and no fight will occur. I would have fought for my childs bag in a heart beat.
Teachers seize student property often.