Oldest cards: I have six 1951 Topps Redbacks. All were bought just after I graduated from college at two different card shows.
Before that: A 1952 Topps card of Pete Runnells. It's in fair shape, but even that might be kind. I bought it in high school through mail order. At the time, I thought it was incredible to have something that old, and I didn't care that it wasn't perfect. I still have that card, and I still don't care that it's not perfect.
And, before that: In eighth grade, I traded with a friend for six 1965 Topps cards. They are in good to very good shape. I don't recall how my friend got those cards, as 1965 was well before we were buying cards ourselves. I seemed much more impressed with how old they are than he did. I've since replaced those cards with ones that are in better shape, but because of sentimental value, I've got those original six tucked away in a box.
I love to trade! Check the top couple of paragraphs of my profile to see my general trading desires. If you're uncertain if I’ll take a certain trade, message me and we can figure out something.