There is a benefit to my parents keeping seemingly everything. I found a bunch of paystubs from my first post-college job, and they don't have any 401K contributions listed.
They're from 1999-2001, though, and I worked there for an additional four years. I'm guessing I didn't opt to contribute to a 401K then, either, which of course was a bad move, but I think this is enough to put to rest the mystery of "what happened to the 401K from my first job?" I had 401K from a job that I had for less than a year, and the company that administered that tried pretty hard to mail stuff to me, even after I had changed addresses, so I think that even if I had a forgotten one, someone would have tried to get in touch with me.
RIP, possible small amount of additional retirement funds.