Note that horse chestnuts (aka "buckeyes"), besides (as you say) being unrelated to standard chestnuts, are toxic. Just handling them is not a problem, but eating them is definitely bad news. Native Americans used to grind them up and use them to stun/kill fish.
Very bad news Indeed! Upvote for the PSA word of caution. I had a neighbor years ago who used just a few pieces of one as garnish on a soup. Made him horribly horribly sick; he survived without medical treatment, but attributes that mostly to the very tiny amounts he ingested.
