how to cook Symplocarpus foetidus
No, I do not have information on safely preparing Symplocarpus foetidus (skunk cabbage for human consumption. According to NCSU's online "Plant Toolbox", Symplocarpus foetidus contains calcium oxalate along with "unknown toxins". AMA Handbook of Poisonous and Injurious Plants also mentions "calcium oxalate and questionable unidentified protein".
Calcium oxalate is also found in the leaves of other plants including rhubarb and taro (Colocasia spp.). In nature, calcium oxalate is a feeding deterrent for herbivores. While there are many examples of humans successfully detoxifying plants for consumption like cassava (Manihot esculenta), without credible information on all the toxic compounds present or how to break them down, I recommend that you do not attempt to eat Symplocarpus foetidus.