

Wikipedia honestly kind of sucks for mushroom information, the information is very general and they only cover a handful of species.
Region-specific resources are the best but I don’t really know any for your region so I’ll recommend MushroomExpert.com which is a good site for general North American mushroom info. Here’s the page on inkys you may want to check out.
You’re missing a very important detail: what part of the world did you find this in?
It seems like it’s something like L. repraesentaneus though the KOH reaction on the cap should have been red. 15-20 minutes should be more than enough time for a KOH reaction but if you waited too long between picking the mushroom and putting the KOH on the cap you may have gotten a false negative.