See the Shaggy Parasol mushrooms? They were not there two or three days ago. Yet Lammas comes and they burst forth, full of fungal goodness.
Here just north of the Colorado-New Mexico line, August is the heart of mushroom season. You can find them at other times too, but your foragers are itchy-footed when the late-summer rain clouds collect along the mountains.
All Paganism is local, so I am thinking: Who is our mythic mushroom guy? He is not cut down to be reborn — he just appears overnight.
The Algonquian tribes have a word for this, although not a guy : puhpohwee, “to swell up in stature suddenly & silently from an unseen source of power.” https://www.amazon.com/Puhpohwee-People-Narrative-Account-Ahnishinaabeg/dp/1879528185