Need A Place To Start Looking.

That'll be a challenging one. Wish I had time to poke around, but am heading to work. First thought, though probably wrong, is perhaps a very crude Zeus/forepart of Pegasus, as from Iolla. Similar to:
http://www.coinproject.com/siteimag...81626q00.jpg
https://www.acsearch.info/search.html?id=7214601

Although the Λ (that may be visible at the top of the reverse of yours) works for the ΙΟΛΛΑ of these issues, it's a stretch. I'm not confident. Probably different reverse imagery altogether. No time to devote to it now, sadly. Maybe tonight.

Ruger, to continue where I had to leave off this morn...This is just speculation, so take it with a grain of salt. I suppose my first inclination - that is, the forepart of Pegasus, right - is likely correct. At least it's my working theory till someone kicks in with something more definitive. The corrosion, wear, and maybe a minting error or weak strike make it a little difficult to see:



I would guess it's from Mysia, with a Zeus obverse. This iconography was common, and emissions with it ranged from very small (less than a gram) to, apparently, almost five grams, with measurements from around 10 mm to 17 mm, based on what I've seen.

Which Mysia mint is difficult to determine, at least for me. I think that Adramytion/Adramytteion and Iolla are distinct possibilities, although Lampsakos might be a contender. All used the Zeus/Pegasus forepart iconography. It seems to me that, on your coin, an A or Λ may appear to the left of the wing (assuming that's indeed a wing!). Some of the issues of Adramytion/Adramytteion have an A in that spot, apparently sometimes rendered more as a Λ. It's part of ΑΔΡΑ. On the other hand, some of the Iolla coins have a Λ in that general area, part of IOΛΛEΩN.

Here are a bunch of various Mysia issues of different sizes, from several different cities, just for comparison of the imagery. The OP coin is top center.

WOW!!!! Thank you @Bob L for all the time and research you put into resolving my identification issue with this coin. I believe you've nailed it again. I'm thinking the far right (3rd row) is as close as I'm going to get as an exact match. Thanks again.