Here's the first cache located within the Dallas city limits, and the 17th oldest 15th oldest active cache in the state.
Hillcrest Park is probably the least utilized park in the city. Most people don't even realize that it's a city park, and not just undeveloped land. There's no parking facility, so I would suggest parking on a side street, or in the nearby church parking lot to the south (if it's not being utilized, of course). This is a two-stage quest. There is no cache at the first stage, only the coordinates to the actual cache.
I don't recommend this immediately after it's rained, or at night. The reason for the "Dangerous Area" icon is because the easiest path to the final may take you to within a foot or two of a cliff that drops 30 or more feet down to White Rock Creek. Watch your step!
Update 26-Oct-2014: The once slightly dangerous path along the creek has been paved over with a new hike & bike trail. The final stage is actually pretty close to its original spot. But if you have the old coordinates, you should get the new ones from the first stage (which was also moved a bit). Finally, the size is now a Small, instead of a Regular.
Cache camera pictures - retrieved September 23, 2003