I have seen a few of these. It's generally compression of another coin that presses the letters onto the rim and yes, I have found them in bank rolls. Odd, and I've even posted at least one such coin here myself, but I am convinced that it is all just a compression thing and has nothing to do with the minting process. Note that TRUST is impressed, and reversed (or is that mirrored?), sure signs of things happening after minting with the lettering coming from another coin post strike.