Mine was a 1931 Mercury Dime (yes, for my prime number set). Took me a long time to find one I wanted. Your typical dealer at a show will have a case full of late dates in high grades, some 21s in various circ grades, maybe an AG-G 16-D, a couple uncirculated early dates, but almost nothing in between. Patience paid off, though. It's an MS65, not designated FB.
I got a coin that reminded me of this thread yesterday. It's a very common type, worth a quarter on a good day. And yet, until yesterday, I'd never even seen one in my 5 years of collecting world coins.
Oddly missing? In nearly 50 years (actually 48) of specializing in capped bust halves I have never owned an 1832 large letter reverse. It's quite common in pretty much any grade one could wish. I'm honestly not sure why I've never picked one up.