Awesome hunt! One time, I found a half wheat penny. Someone took the obverse off. That 1990 might missing the copper layer. Never found one but seen other people find them. I believe it’s an error. The 1974 looks like a clipped planchet error.
Did a similar search in 3 box's or 75 dollars of rolled pennies recently. They were mostly Canadian but had some US...the oldest US was a 1920 and found 1/2 dozen in the 40's. Was able to build a complete Canadian album back to 1938 including a 1931. Our 3 grand kids went through the penny stash and each built a nice album as well....regards....
Cool. fun video. I did this alot with quarters, looking for junk silver. I was also able to fill all my books in a few months. I haven't started doing penny books, but I just might now.