Harvesting Urtica dioica is a touchy endeavour. Gloves, clippers and a bin or box are necessary, as well as long sleeves and pants if wading into rank growths. Once the turgor pressure has dropped (i.e. the plant wilts), the stinging elements are harmless. I harvest the plants until they begin to flower. They can cause digestive upsets if harvested any later.
If indeed your "nettle" is U. dioica, then yes it is most certainly an edible. However, in these parts, there is also the Horse Nettle, Solanum carolinense, which contains solanine, a dangerous substance to ingest. I second Tyler's call to use the latin, and be sure of the id.
