bgreeny, this is our best guess at what you have. There aren't many small ancient silver coins with a bearded head and a rider on a horse, especially not with letters underneath the horse. So this is a pretty good guess!
The ancient Iberian peoples did a lot of trading with the Greeks and Romans, so they came to know of their coins. They soon started striking their own, carrying inscriptions in the Iberian languages. These specific coins have inscriptions in the Northeastern Iberian script. It's written from left to right, and reads BELIGIOM or BELIGIO, depending on the exact coin type. The mark(s) behind the bearded head read either 'BE' or 'BELI', again depending on the exact type. These are very valuable coins, as listed below:
worn: $200 US dollars approximate catalog value
average circulated: $400
well preserved: $600
Amazing specimens with virtually no wear on the surfaces and beautiful toning can reach catalog values of up to $1000.
There is also a version in base metal. The name for this coin is borrowed from a Roman denomination - 'As'. They look just like the silver ones, but they are bigger and struck in bronze.
average circulated: $120
well preserved: $350
Since the writing of this article, bgreeny has contacted us by email. His coin is similar to the one shown on this page, but carries a different inscription underneath the horse. His coin is from the ancient city of Bolscan, not Beligiom. There are also other, similar coins with different inscriptions. Values fluctuate a bit, but are not too far off from those shown on this page.