Today I have been sorting through the last 5-6 years' worth of notes. Since I have to pay to ship these across the country, everything unnecessary must go.
Notes relevant to research I'll keep; likewise copies of articles, which I keep either for reference or because I may assign them in a class someday.
But do I really need to keep all my printed-out class notes? When the same files are on my hard drive? I tossed the ones for classes I don't anticipate teaching in the near future (or, perhaps, ever again), but I'm undecided about the others.
Notes for graduate classes can also be purged, I suspect, especially since I haven't really looked at most of them in ages.
Terrifying discovery: my senior thesis. I'm afraid to look at it too closely.
Edited to add:
I did throw away student evaluations of my grad school teaching. I've taught my own classes for years now, no one cares how well I led discussion sections at the age of 25. Evaluations for my own older courses may go, too--I'm undecided.