Verdict: In moderation
While some store-bought mushrooms are safe for dogs, many wild mushrooms are highly toxic and can cause severe illness or death. Due to the difficulty in distinguishing safe from toxic varieties, it's best to avoid feeding dogs any mushrooms unless positively identified as safe by an expert.
Mechanisms vary by toxin: amatoxins cause cellular damage, particularly in the liver and kidneys; muscimol and ibotenic acid affect the central nervous system; psilocybin has hallucinogenic effects.
Various, including amatoxins, muscimol, ibotenic acid, psilocybin, and others depending on the species.