I got these today at my local B of A. Not really found in circulation, but perhaps close enough? A 1935-C and a 1935-F $1 silver certs, and a 1974 $50 frn. None are really worth keeping but I might hold on to the SC. I believe the 1935-F note is the first I have seen with a Z starting the serial number. I am not up to speed on SC serial numbers, but I think that the letters have to do with the plate number? I could be(and frequently am) wrong.