Possible error coin, Reverse only .850" diameter copper

Could also be that that side has just been ground away. What is the size and weight?

.830 diameter and weight is 1 gram.  The blank side doesn't seem to have any tool marks from being machined.

It doesn't really match any coin I could find.

The coat of arms is from the Austrian Empire, and the closest match is this one: N#2082

Slightly smaller at 19 mm instead of your 21,1 mm, and a lot heavier at 3.35g instead of your 1 gram. If it is a similar coin, with some measuring errors, then the weight loss can be explained by a lot of material having been removed. 

Or it is just some token or ornament bearing that coat of arms.

Indeed the differential weight loss from the Austrian Empire piece pretty much confirms the PMD outcome and why its uniface. 

My concern is that the Crown at the top and Shield in the center are different  than the Austrian or Austro-Hungary coins.

It may be then its a token or some non-official coin variant? I collect some German States such as Wildman issues but best do an E-Mail attachment photo to some Austrian coin expert. The Numista catalog already gave you these legitimate regal low denomination issues as possible matches that do not match this crown in your coin - since I tried that myself - so hence my conclusion in the opening sentence.

Looks like a token to me.

Slipstreamed

Looks like a token to me.

I love your avatar, what is it, a Pacman planet thing? Looks cool.

Thanks! It’s the space ship from the movie Heavy Metal. Piloted by two very amusing characters.