Hello, Brian -- Nice! It sounds like you have a silver 8 reales coin from the Mexican State of Zacatecas. These coins can be quite valuable, especially if in good condition. Most all of them you see are worn, but some are worn more than others. If your specimen has wear but no damage such as scratches, stains, cleanings, gouges, spots, and the like, it should be worth several hundred dollars. The coins in our secondary picture, annotated KM 189, is in excellent shape and it sold recently for the retail price of $2100.
Here are some VERY APPROXIMATE values:
worn: $50 US dollars approximate catalog value
average circulated: $400
well preserved: $1000
Brian, if your coin looks anything close to either coin in our two pictures, you should enlist the help of a knowledgeable coin collector or coin dealer. There are many twists and turns with this coin that can raise or lower value. On CoinQuest we can only offer VERY APPROXIMATE guidance.
You can see from our two pictures that different types of this coin were minted for Zacatecas. Coin collectors know these by their Krause Mishler numbers KM#189 and KM#190. The main differences are the orientation of the date relative to the shield pattern and the castles in the shield are replaced by flowers. To keep things exciting, there is also a KM#187 version. This is why it is important to research you coin further with experts.
One good way to access several coin experts at once is on the CoinCommunity.com web site. Here you will find many enthusiastic numismatists (coin collectors) who enjoy talking about coins and are more than willing to share their expertise. In fact, the KM#190 in our main image comes from MathieuMa, a pillar of the community.
CoinQuest thanks MathieuMa for use of his coin photo, and we also thank Heritage Auctions for permission to use the KM#189 photo.