I found 3 1939-S Jeffys in one box... keep at it, Mike, and I'm sure you'll find 'em sooner or later. Haven't found any of the other key Jeffersons, though, unfortunately... over $4k searched now too.
The 82 cent is interesting, between large and small dates and copper and zinc, there was 7 different coins minted, not including the proof. As to the early 70's S mint coins, they are out there and you would be surprised how many are in almost uncirculated condition. I guess many people saved them but finnaly dumped them back into circulation when the price never really rose (because everybody hoarded them).
That one's real hard to get. I had a washington/eagle clad circulation set with a hole for the 68-d, nothing else. Took me forever to find that one.
If you have an album with the plastic windows, it will include all of the regular issues, including proof-only issues. Anything S-mint from 1975 onward will be proof-only. Speaking of S-Mint Memorials, I remember getting all excited back in '68 when I heard that the San Francisco Mint was going to resume making cents and nickels for circulation. I looked and looked for them, but since I was living in the middle of the country, all I found were P- and D-mints. I ended up responding to an ad in a 1968 Coins magazine which stated "S-Mint pennies are bountiful here in California. Send me your penny and an SASE, and I will send you an S penny". So I sent the lady a penny, and spent 12 cents for postage (6 cents each way), and got my '68-S penny. I was so excited about it, I took the penny to school, and lost it on the playground! I never found a '68-S in change after that! But I have since found several in bags of coins I've bought from charities here in Japan! Quite a few '71-S's too.
Not exactly circulation, but I could never, ever find a 1958-P Washington quarter in a silver junk box. I found almost everything else within reason in that series that way. I've also never found a 1950-D nickel, and in many, many years of searching I've only found one 1950-P. Lots of war nickels, though.
I actually did find the 50-D Nickel, but bought the 38D & 39D (for now). Also bought the 55 Frankie & the 48P, ended up getting another 48P vis rollsearching. Still looking for the 70D Kennedy.
I found a '58-P quarter in a junk box not too long ago. The dealer had just bought a bunch of quarters and put them all in the box. The coin was in beautiful condition, too.