Then you can have everyone dress up like farmers, which would be something like this:

Clothing–

–blue denim overalls with at least one patch, hole, almost-a-hole, or burn mark from welding. Faded is better than not for this. Galluses (the things that hold the shoulder-straps up and together) must be removed and replaced with large paperclips.

–blue denim longsleeve shirt, also faded and with same holes/patches/burn marks as overalls. (this is worn under the overalls, and if worn regularly for farming, the shirt will have a fading pattern showing where the overalls were)

–work boots. not new ones, mind you, but the most worn-out ones you can find. or, if you have to, new ones on their way to being worn-out. (round laces, redwing is a good brand for this. last pair I saw lasted about 3 years, which is incredible for a farmer)

–beat-up-worn-out-dirty hat. must be straw or cloth, must look like it has been trapped in a tractor engine more than once and lost in *gasp* the farmer’s pickup (always dirty and full of farm-junk, also used to transport half-dingo cow dogs who….get over excited.) If you can’t find an acceptable hat, a baseball style cap with the emblem of whatever cotton gin, grain elevator, or seed company was giving them out for free this year. the cap can be new or dirty, it’s your choice.

Make-up:

a dark, reddish-tan on the face, ears, neck, and hands is essencial. This is normally acomplished by years in the feild in the above outfit without sunscreen, but you could probably create the same effect with make-up.

Props:

–dirty red or blue bandana. clean is ok as long as it is in the back pocket of the overalls.

–checkbook with notes written all over the back. this goes into the bib pocket along with the empty tally-book and wallet.

–broken pocket-watch (crystal shattered, rest works fine. wall-mart has good starter-watches, just put in side pocket of overalls with other props and lay under the pickup trying to fix some unknown problem with the engine and it will turn into the perfect farmer’s watch.)

–pocket-fillers ie: coins, sprinkler pads, washers, nuts (metal kind), bolts, cotten seed, wrench, knife (rusty or utility-style), any part of a (pre-1986) tractor, combine, or pickup that is small and light enough to carry in a pocket.

Glasses (wire-frames, big lenses that turn into sunglasses when sun is bright, preferably with one that cracks without reason or warning) and dirty earplugs are optional.

You might also add used parts of the above-mentioned farm machinery to different corners of your area for extra decoration.

Well? How’s that for a good theme? It sounds like a winner to me. (And if the judge has an agricultural background, you’re sure to win!)
References :
In case you haven’t realized by now, I live on a farm….and the farmer costume is what my dad wears to work every day! (See! I wasn’t just conjureing up the image of the "steriotypical american farmer". This one really exists and has been farming for more than 30 years. )