We all have had things that we have gotten rid of at one point or another but wished we hadn't.
I had a good friend who had his own autograph business. He'd chase down celebrities full time in Los Angeles, and he would often let me have first crack at his really good stuff. He would get all of them himself, so it was super cool to pick through his collection, knowing they were all authentic.
Over the years, I amassed a pretty cool collection of stuff.
At one point it got kind of out of control, so I sold a bunch of stuff I had on ebay.
What made me think that a Mick Jagger signature, in silver paint pen, on a Herb Ritts photograph would be a good idea to get rid of I have no clue, but have absolutely regretted selling that thing since I packed and shipped it off when it was sold.
People will come to my house and comment about how cool the collection is - I mean it's striking, one of a kind stuff- but when I go to say, "Thanks, glad you enjoy it," I hear this little voice in the back of my head saying, "Well, it could have been a lot better had you not sold the God of rock's autograph on the coolest picture ever, goof head."
Also- I traded away a bunch of late 1960s, early 1970s baseball cards- Rose, Jackson, Bench- for a handful of Intellivision games.