Last summer when I had energy to sort through some stuff I hadn't yet, I found a bunch of old deeds (1940s and 50s) from where my mom grew up. I showed them to my aunt when I visited her last summer, and she said my mom had taken them from my grandmother when she died in 1989 and meant to return them to the county court or wherever and never did.
I'm waiting until I finish in case I find more, and I know who to contact there, but yeah. I have papers that my mom had from her mom.
My aunt said to keep tax returns for seven years. So I suppose I can shred the 2017 ones now whenever I find them, and any older ones.