I appears early on in this thread some folks could stand some medical training to prepare.
There are actually some schools/training out there on this very subject, well worth the time to take.
There's a group called OklahomaWildcrafting that teach classes on foraging for food and medicine. They do a hike every season (all 4) that teach how to find edible plants, mushrooms, and medicinal uses. I've never been able to get in as it usually fills up on day 1. Every year they do a big wildcrafting fair where chefs from really nice restaurants (ludivine etc) use only the gathered ingredients.