Very nice find!!!
I should tell you that I have been warned about hunting in Chicago parks. Some detectorists have been run-off by the cops. Don't know what the big deal is. I've read posts by another hunter who does OK in Chicago parks and he's never had a problem. So I'm just passing along what I have heard. I think if you stay out of the lake-front parks, you should be OK. Looks like it's open-season on the beaches though.
The Cook County Forest Preserve also has a strange rule; you can swing, but you're not supposed to dig. I've spent lots of time swinging and digging in front of those cops and they don't seem to care - they almost seem amused. Yet, others have received tickets for doing the same thing.
I've heard that DuPage county is real strict; you can't even swing a detector in their forest preserves. Yet I'm fairly certain that DFX-Gregg swings out that way and I've never read any bad news in his posts.
HH
Rich