For me, I would imagine that I couldn't imagine giving away my rainbow-colored socks. They're awesome, as they've got all the little slots for all the little piggies to keep them separate and warm...and they've even got smiley faces on each one.
Honestly, I don't like 'stuff', so other than my ever-growing tool collection, most of everything I have gets given away after a time. If I don't use it, I don't need it. I'm extremely practical...to a fault. Probably the only thing I can think of that others would want me to throw away is my Carhardt coat. It's a couple thousand years old, ripped, shredded, and just generally nasty, but it's mine, and it's the warmest thing I've ever owned.