Is it wrong to take someone elses gift?

I have a large family and at xmas we gather around and exchange gifts. Sometimes people dont come until the next day so we save them. However, one cousin has not come for her gift, it's been here for 6 months, parts of it had to be thrown away because it was food. Her family has a bit "I'm better than you" attitude and they are fairly well off. Point being after 6 months there are a few gifts for her still here and I dont think she will ever come for them. Would it be wrong for me to have them? Being I could use them where as she's letting them waste?