Considering how many different varieties of psilocybe their are in the wild your chances are pretty high;
Conocybe cyanopus • Conocybe smithii • Gymnopilus aeruginosus • Gymnopilus liquiritiae • Gymnopilus luteofolius • Gymnopilus purpuratus • Gymnopilus sapineus • Gymnopilus spectabilis • Inocybe aeruginascens • Inocybe corydalina var. corydalina • Inocybe tricolor • Mycena cyanorrhiza • Panaeolina castaneifolia • Panaeolus africanus • Panaeolus bisporus • Panaeolus cambodginiensis • Panaeolus cyanescens • Panaeolus fimicola • Panaeolus olivaceus • Panaeolus papilionaceus var. papilionaceus • Panaeolus sphinctrinus • Panaeolus subbalteatus • Panaeolus tropicalis • Pluteus salicinus • Psilocybe • Psilocybe atlantis • Psilocybe aucklandii • Psilocybe australiana • Psilocybe azurescens • Psilocybe baeocystis • Psilocybe bohemica • Psilocybe caerulipes • Psilocybe cubensis • Psilocybe cyanescens • Psilocybe fimetaria • Psilocybe galindoi • Psilocybe graveolens • Psilocybe guilartensis • Psilocybe mexicana • Psilocybe ovoideocystidiata • Psilocybe quebecensis • Psilocybe semiinconspicua • Psilocybe semilanceata • Psilocybe strictipes • Psilocybe subaeruginascens • Psilocybe subaeruginosa • Psilocybe tampanensis • Psilocybe villarrealiae• Psilocybe weilii• Psilocybe zapotecorum.
Concentrate on area's with grazing land and cattle.. People say finding them growing on cow shit is a myth, but it's not as much of a urban myth as they would think, I found a whole heap of cubensis growing right out of some cow shit last year and they where HUGE! Obviously well nourished on cow poo.Their where miles of fields and miles of shrooms...
Although not all of them where the magical variety they where growing in close proximity to some Amanita virosa... Nice and Deadly!
Bear that in mind before you go putting anything anywhere near your mouth (specially if its growing out of cow shit!), if your not 100% sure what it is, then leave well alone. Last thing you want is your liver and kidneys dissolving just because you where looking for a good time.
I'm going back that way this year not in the US though
but I'll get some photo's and upload em with measurements, going to erm, pick some for further enhanced analysis and some microscopy, who am I kidding I'm going to get high LOL
Dry em, powder em and store em and another method I've heard about is putting them into honey! As honey is a natural antiseptic it helps ward off moldy woes later on if your thinking of long term storage!
It's just a little awkward explaining that one to a guest who helps themselves to your honey jar "NOoooo!, that's not normal honey!!"
Also check the laws in your state, pick and cultivating could land you with a fine if caught and putting them in your mouth can be more trouble than its worth! Especially if you make a mistake and spend the next 24 hours having your guts pumped out with salty water... Downer!