I was taking a walk around Oak Knoll Park and I have seemed to misplaced my keys. I've marked the last place where I had them, do you think you could go look for them for me?
Oak Knoll Park lies just north of the Clayton/Richmond Heights border. It has a long an interesting history, the parcel of land and two mansions being owned by some wealthy St. Louis merchants. For 25 years, the two buildings were leased to Museum of Natural Science, until they moved in 1985 to open the Saint Louis Science Center. You can read a more detailed account of the park's history here: http://www.claytonhistorysociety.org/pdfs/Oak_Knoll_Park.pdf
Note: the hint gives you the general area in which you should be looking. It doesn't reveal the hiding spot. Looking at the hint may be recommended since some of the "wrong" places to look may be tricky to get in and out of.
When replacing the cache, please rehide it such that it is barely visible to those looking for it.