For me, psilocybin catalyzed such pivotal decisions as moving out of my parents' house, getting married, and changing careers. It seems plausible that it would be relevant to the founder effect (https://www.genome.gov/genetics-glossary/Founder-Effect) in other animals.

Sometimes we need a little shove to start doing new things that end up being advantageous. There's no reason to believe that we're unique in that way. If that shove is advantageous enough to be worth returning for a second shove, well now you've got the seed of a cross-kingdom relationship.

But that is outside of the timeframe you'd be spreading spores. Deciding to move out in a month isn't doing anything for the mushroom.

Well in that particular case, moving out meant I could dedicate a whole closet to cultivating them. But I don't think that cultivation is a necessary step, merely returning for more is enough to start the kind of relationship where adaptations which allow for one party to help the other are selected for.