I just found a similar button but with a different back. It's an Army great seal button. You can do a search on here for a thread with lots of info on it. Greatcypresshunter has a pretty good list going of all the varieties. According to what I read, yours is a later version that has the raised rim....like mine.
Yea, my first time was all it took for me too.....Now its 6 weeks in and I already have 3 detectors and another planned for the end of the year....Good luck with your new addiction....