At the first-ever CannaFest in Virginia Beach on Sunday, you can see a custom car show. You can hear half a dozen musical acts, including one of the ’90s’ hottest R&B acts, Blackstreet. You can learn about uses for CBD oil, hemp and other cannabis-derived products. But no smoking, buying or selling the plant at the event, though carrying a small amount of if it became legal in Virginia on July 1. Anthony Brown, the…