Just had to use that subject title to get "Mint B's" attention. I had read some time ago that some of you marked your return coins with a felt marker just to see where they go.
Answer: a whole bunch landed in Central Minnesota in a Wells Fargo box I was "lucky" enought to get. So I hope this answers your question.
Hey, it was fun to find and hope fun to find out where they go. But I have enought "B's" now so feel free to send them anywhere else.ha
May all your coins be copper (right, the "B's" were zinc) but then no serious copper collector would deface a beautiful "copper penny"
I don't think there is a "B" mint mark here in the USA. Maybe you have D's with a die crack. Or counterfit.
edit. Reread your post oops. lol would take a very long time to mark cents.
Selling Ryedale sorted USA cents 1.5 each + shipping over 500fv 1.5 each +1/2 shipping If you pick up 1.35 each located MT/ND boarder. after Ryedale sorting they are hand sorted to remove canadian then rechecked with Ryedale to insure all copper and count out $50 FV then placed in cloth bags and sealed with #1 copper wire.