My twin brother.

I got my dad a coin from his birth year, but it was 100 years off - I gave him an 1831 penny. Then, later, I said I was sorry I was 100 years off, and got him one from 1731. I kept it up with 1631, and I think I was able to find a coin dated 1531. Unfortunately, if I wanted to keep it up, the only dated coins from 1431 and earlier that I know of are Islamic, and I would have to do some math since they use a lunar year rather than a solar one.

-- Tom