I’m a mushroom forager but there’s no way I’d ever eat an iffy shroom. False morels and thimble caps are in that category and are too be avoided. There are only a dozen or so proven safe wild mushrooms in my locale. I stick with those exclusively.
I read recently, that False morels (and even true Morels, but tona much much lesser extent) contain or matabolize in the body into HYDRAZINE! Hydrazine is the highly toxic hypergolic rocket fuel we used to land on the moon!