Sweet Sister and I planted a letterbox today in my old college stomping ground. As far as I can tell--although there are zillions of geocaches--it's the only letterbox within the town proper. If you want to hunt, here's the clue:
Bananas For Gorillas
In southeast Kansas, there's a lovely little college with a gorilla of a mascot. Find the campus, then find the football stadium. Behind the stadium you'll find a lake and the gazebo pictured. Cross the bridge that's near the gazebo to get to the island in the center of the lake. Once on the island, follow the path to the beginning of the other bridge. Just before you step onto the second bridge, there will be a tree to your left with a hole near the bottom. If you poke around there, you'll find a stamp any gorilla would love.
6/2/08 EDIT: This letterbox has disappeared. :(
(Letterboxing: P2 F5 X0 / Geocaching: P0 F2)