It doesn't look like 小人人 refers to the mushrooms. It refers to the hallucinations, and is not necessarily expected to include visions of people:

> "No!," she said, most emphatically, "They are real. I have seen them myself!"

> Miss Oh clearly remembered the hallucinations that began that evening and continued into the next day. The walls moved and shifted in geometrical patterns and strange shapes appeared.

> "I'm sleepy all day," she said in English. "I see them. And I see flies bigger than the actual one, perhaps two times big. I see little insects. Not all the time, but when the water splashed out." She apparently became fascinated by the dripping kitchen faucet, for each drop would, upon hitting the sink, sprout wings and legs and crawl away. And she remembered, very clearly, staring intently at the bows of her shoelaces until they turned into butterflies and fluttered off.

The paper devotes quite a bit of text to explaining that the mushrooms bearing this quality have no specific name, and in fact are not distinguished from non-hallucinogenic mushrooms at all. They are referred to by their property of turning blue when handled, which is a property not exclusive to the hallucinogenic ones.

https://sci-hub.se/https://www.jstor.org/stable/40390492

Interestingly, despite this prior paper being cited by this press release, and despite the fact that the prior paper devotes almost a page to describing the difficulty of identifying which mushroom(s) might be hallucinogenic given that the people of Yunnan never draw any distinctions between them, this press release assures us that identification of the hallucinogenic species was as simple as asking market vendors in Yunnan whether this was the mushroom that caused hallucinations.