I got got this way with some bonds that my grandmother bought me when I was born. They were some kind of long term bonds that took a very long time to mature. I had no idea that I even had them, they were in my parents closet or something, and my parents completely forgot about them as well. I was like 35 when they gave them to me. At that point they had been fully matured for a very long time, but because of inflation, the buying power of the money earned actually made them worth less. I forget the exact numbers, but it was like:

$100 matured to $200

But a quick lookup with an inflation calculator, $100 from the year I was born showed that it had the same buying power as $280 now. So the $100, while going up in number, actually went down in value. Certainly better than keeping the $100 under the mattress, but that sucked.

Oh and it was significantly more than $100. Nothing near life changing amounts of money, but probably money that I could have used earlier in my life - to help with student loans or something. When there was less inflation.