Hello Alias Blu and welcome. 
As noted above, it is impossible for a coin to be struck only on one side. So whatever your coin is, it is not a mint error. Your coin has been ground down, the same as the one in the OP - only the grinding has been heavier and worn away the silvery clad layer on that side, revealing the copper core underneath. I would predict that this coin would weigh considerably less than a regular quarter, and less than the 5.5 grams of the OP's coin. The spiral pattern on the "blank" side clearly indicates some kind of lathe has been the culprit.
The "prominent rim" has been made by whatever lathe or machine has been used to do the grinding.
As noted above, it is impossible for a coin to be struck only on one side. So whatever your coin is, it is not a mint error. Your coin has been ground down, the same as the one in the OP - only the grinding has been heavier and worn away the silvery clad layer on that side, revealing the copper core underneath. I would predict that this coin would weigh considerably less than a regular quarter, and less than the 5.5 grams of the OP's coin. The spiral pattern on the "blank" side clearly indicates some kind of lathe has been the culprit.
The "prominent rim" has been made by whatever lathe or machine has been used to do the grinding.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis





















