Don’t eat them. No, seriously, don’t. At least not raw. Cadavaberries are poisonous and deadly, often used in sinister ceremonies of ritual sacrifice. The cadavaberries on Ashenfall are equally toxic, but can be coaxed into good behaviour with the judicious addition of fire.
The toxins can be burned away, providing a surprisingly pleasant tasting berry beneath. But, one must be careful, for preparing them wrong is the last mistake someone is likely to make.