How do I become less attached to things?

Things in my life that I remember seeing/hearing/looking at/using as a child really mean a lot to me, even if it's something stupid like a toaster. I really wish I wasn't like that, so I could have less stuff at home. Whenever I even think about giving something away, I try to get that thought out of my head. Now, I'm not a hoarder, it's just the things that I remember even slightly are hard to part with. Books, in particular, I absolutely can't stand losing. I realize that it's stupid to feel that way, but I still do. How can I become less attached to my stuff?