Aaron Rodgers, Jaden Smith and Rick Perry are all speaking out about the benefits of psychedelics at a conference in Denver

Months after Colorado’s voters decided to join Oregon in decriminalizing psychedelic mushrooms, Denver will host a conference this week put on by a psychedelic advocacy group bringing together an unlikely cohort of speakers — including an NFL star, a former Republican governor and a rapper. The conference and the thousands expected to attend it is an indication of the creep, or perhaps leap, of cultural acceptance for psychedelic substances that proponents say may offer benefits for things like post-traumatic stress disorder and alcoholism. Still, medical experts caution that more research...