I would like to know a few things on the state of edibility of stinkhorns and lichens: I have heard that all known stinkhorn species are edible, but I've also found mixed messages on the web about their edibility in mature form. I have some culinary ideas for mutinus elegans stinkhorns, and I want to make sure that I don't get sick or die from eating them. So what I'm asking is are they poisinous, or not? Also, I want to know if lichens are safe to eat. If so, which species? Thank you!
Fairly sure some (whether all?) stinkhorns are edible in the 'egg' stage; I don't think any are when mature. Lichens - most are not edible. In general, they're also too rare / slow-growing to be harvested.
Ditto on what MichaelF said. A few lichens have been used medicinally, like Usnea and Lobaria. Generally since some lichens contain powerful substances, you'd want to be very careful not to poison yourself. And since they grow so slowly, you'd not want to damage their colonies unnecessarily. Historically "rocktripe," which I think is Umbilicaria, was eaten as a survival food by explorers in the arctic, but since it apparently tastes awful and you have to wash it heavily to make it edible, it hardly seems worth it :-). A First Nations people apparently steamed Bryoria for food, but I have not tried this yet. I bet mature stinkhorns would taste worse than they smell :-)