i have been keeping all of the fancy serial numbers that have come my way (3 or more doubles like 223344, triples 333, quads 4444, patterns 121212, and anything along those lines). i also have a few error type notes like the 2 solo pictures. the first is the 8 has an ink spill and the second the serial number on the top right is lighter than the other (faded).
A week or two ago i went to the A.A. museum and saw an unexpected exhibit, there was a wall full of old us paper money from before the civil war. what was very interesting about this type set was that all of the different bills depicted African Americans, usually on plantations, but some were in other settings. this was also the first time i have ever seen a 3 dollar bill and all of the designs were fascinating. in my opinion the paper money in the pre-civil war era was much more eye appealing than the bills nowadays. there was also an abundance of depictions of woman, which was surprising to me because back then they didn't share the same equality as now and today there are people trying to get a female face on the US currency while back in the 1800s there were plenty of women depicted on the paper money. another piece of history that i learned was that before the civil war each state had their own banks, sometimes cities printed their own money, which made it a little harder to trade outside of states but it is really cool the types of designs and the history behind all of them.