The Nevada Day Treasure Hunt gets underway tomorrow (4th Oct).

The treasure (which has been hidden on public property somewhere in Carson, Churchill, Douglas, Lyon, Mineral, Storey, or Washoe county), is a small acrylic square containing the Nevada Day Treasure Hunt message.

According to the rules there is up to $1,000 prize too
(but the rules look like they might be a little out of date - at least they refer to 2009 which could just mean someone forgot to change them after last year's hunt).

No purchase necessary, but you have to register to enter - full details can be found here:
Nevada Day Treasure Hunt

I came across this hunt via this article which you might find of interest too:
Nevada Day Treasure Hunt kicks off Monday | NevadaAppeal.com

Good Luck