The best blackberries are the wild ones. In Oklahoma, the berries are picked in the weeks following the July 4th weekend.
Problems
When harvesting blackberries, watch out for chiggers (also known as berry bugs). These are small mites that can cause rashes and itchiness when they bite.[1] Spray DEET all over (if you don't mind using DEET), or use a suitable alternative, especially on the ankles, waist and cuffs.
Uses for blackberries
Cobblers, Wines