Twenty years ago, old-timers will tell you, Frisco was dirt roads and corn fields. Now it's rapidly becoming like the rest of Dallas. There remains one patch of dirt amidst all this urban sprawl where one can pet a donkey, ride a horse or simply smell the aroma of fresh manure. It's the Frisco Horse Park. It's right off Highway 121, across the street from 7-Eleven, down a rutted dirt road, through a field of dying dandelions, beyond a chipped white fence. The clapboard office, rumor has it, was once a whorehouse. Now it's where you pay $35 to ride a horse for an hour. Better yet, pay $5 to put your kiddo on a pony for 10 minutes. But you better hurry, because before you know it, it will all be gone.