False morel

The name false morel is given to several species of mushroom which bear a resemblance to the highly regarded true morels of the genus "Morchella". Like "Morchella", false morels are members of the Pezizales, but within that group represent several unrelated taxa scattered through the families Morchellaceae, Discinaceae, and Helvellaceae, most often "Gyromitra". "Verpa" species by contrast are in the Morchellaceae and are true morels.
Compared to morels.
When gathering morels for the table, care must be taken to distinguish them from the poisonous "false morels", a term loosely applied to describe "Gyromitra esculenta", "Verpa bohemica", and other morel lookalikes. Although false morels are sometimes eaten without ill effect, they can cause severe gastrointestinal upset, loss of muscular coordination (including cardiac muscle), or even death. Incidents of poisoning usually occur when they are eaten in large quantities, inadequately cooked, or over several days in a row. False morels contain gyromitrin, an organic carcinogenic poison, hydrolyzed in the body into monomethylhydrazine (MMH). "Gyromitra esculenta" in particular, has been reported to be responsible for up to 23% of mushroom fatalities each year in Poland. "G. esculenta"—regarded as delicious—is known to be potentially deadly when eaten fresh, but research in the 1990s showed that toxins remain even after proper treatment. While many people eat false morels without apparent harm, some people have developed acute toxicity and recent evidence suggests that there may be long-term health risks as well. 
The key morphological features distinguishing false morels from true morels are as follows: