Mum...what about Percy's Head Boy badge? I mean, it might be hard for you to give it up, because you'd rather keep it. But it would add weight to the idea of the donation, and keeping it in the trophy room, because it definitely represents an honour connected to Hogwarts. If he asks you why you don't want to keep it yourself, you can say it's too painful of a reminder to have at home, and you're sure Percy would have wanted it to go back to the school, because Hogwarts meant so much to him.

I mean, everyone knew how proud he was of that badge; he was polishing it all the time. We used to tease him about it.

You can have it nicely mounted on a plaque: 'Percy Weasley, In Memorium,' with the dates he was Head Boy. And then once it's at the school, and Dolohov's checked it over, Brutka or Sinistra can slip something into the base.