Pam, I forgot one of the most important item for our memory tree - the star on top is one my mother's father made from tin. It always needs a bit reshaping each year, but means so much to us!
You could use just about anything for a memory tree, as long as it holds a special memory in your lives. How about a scroll of favorite music? A mother's handkerchief could be tied on with a piece of ribbon. Even jewelry. Just as though it means something to you.
I hope when my sister and I are gone, my nephew and wife will continue with this idea.