Souvenir T-Shirts

In my efforts to get rid of things we no longer use, I've been going through upstairs closets where our sons have left behind clothing they no longer wear...

(In all fairness, they occasionally do wear them when they come home for a visit.)

But even I am having a hard time parting with some that have sentimental value...

Souvenirs of trips taken...

Memories of courses taken more than ten years ago!

Which should I give away? Which should I keep?!