You are looking for an unusual micro cache. You'll need a pen (permanent marker is even better) to sign this log. If you can't sign the log, PM a photo of the log (but don't post any spoilers in your online log, please!).
Do NOT attempt to access this cache from the Des Plaines River Trail; the terrain is too steep for that. Approach from the north. No bushwhacking or climbing is required, but stealth IS! You can stand on the lawn and retrieve this cache. This is intended to be an easy, practically park-and-grab cache!
Congrats to knoffer on the FTF!
Photo is of the meadow area near the cache on the day the cache was hidden. Cache is not in this photo; just wanted to share how lovely the park entrance can be mid-summer.