The invisibility cloak
It’s Harry Potter’s first christmas at Hogwarts, and the first time he was given presents! Ron has already opened some of his, one of which being a red sweater. When Harry opens one of his presents, he finds some sort of cloak; as he puts it on, it turns out to be an invisibility cloak! It doesn’t say who gave it to Harry, but the cloak would eventually become an important tool in future adventures.