My first cache was an accidental find. Not sure about the date, but I logged it as 11/8/06. I will return someday to find this one legitimately and look at the logbook to see what I wrote and the date.
"Stone Boy #1"
I was on a short hike to a spot I had been to before a few times. It's a really peaceful place with a great view. The terrain is rocky. I was building a rock tower (stacking rocks on top of each other) underneath one of the rocks I picked up to use was a small tupperware. "What's this?" I opened it up and read the explanation - "Congratulations, you've found it! Intentionally or not!"
I sat there and read all the logs. It was really cool. I wrote something dumb in the logbook, took something, left something, put it all back where I found it and wrote down geocaching.com so I could look it up when I got home.
No GPS unit, so I kinda forgot about geocaching for a few years til I bought an iPhone. I used the iPhone to find my second (first intentional) cache on 5/6/09. "SG014 Daggett Summit" right down the road from my house. It only took a few caches with the iPhone before I realized I needed a "real" GPS unit.