Many t-shirts which are 30+ years old....from my road racing days mainly, although with a few concert tshirts in the mix. Since I lost 40+ pounds, and am down to a weight I last was decades ago they actually fit again. My "prize" possession is an ORIGINAL t-shirt from the Born in the USA Springsteen tour in 1984. My daughter saw it and was like "I totally would wear that." Uh. Never. You'll pry that thing off my cold dead body. So, other than t-shirts, I'd say the oldest thing I wear is a sweater I bought at a second hand store in the late 1970's. I have no idea how old it might be...but it wasn't new when I got it. Paid 10 cents for it.