Maybe
@moxie is right about mushrooms:
From the CBS website
According to the FDA's Food Code, the vast majority of the more than 5,000 fleshy mushroom species that grow naturally in North America have not been tested for toxicity. Of those that have, 15 species are deadly, 60 are toxic whether raw or cooked — including "false" morels, which look like spongy edible morels — and at least 40 are poisonous if eaten raw, but safer when cooked.
The
North American Mycological Association, a national nonprofit whose members are mushroom experts, recorded 1,641 cases of mushroom poisonings and 17 deaths from 1985 to 2006. One hundred and twenty-nine of those poisonings were attributed to morels, but no deaths were reported.
Marian Maxwell, the outreach chairperson for the Puget Sound Mycological Society, based in Seattle, said cooking breaks down the chitin in mushrooms, the same compound found in the exoskeletons of shellfish, and helps destroy toxins. Maxwell said morels may naturally contain a type of hydrazine — a chemical often used in pesticides or rocket fuel that
can cause cancer — which can affect people differently. Cooking does boil off the hydrazine, she said, "but some people still have reactions even though it's cooked and most of that hydrazine is gone."
Federal officials issued their first guidelines on preparing morel mushrooms after a deadly food poisoning outbreak in Montana, noting the toxins in the delicacy aren't fully understood.
www.cbsnews.com