Hi John,
They are called 'position' pins and are fairly common.
Here's an RE Edwards auction - the position pins that I think you are talking about are at the bottom of the first picture (catcher and batter). I also heard they were from the late 1890's and have owned a few myself, but RE Edward is saying 1910. They normally don't go for that much, so I'm guessing the more detailed pins at the top are what ran this particular auction up so high:
http://www.robertedwardauctions.com/.../2005/826.html