I see it differently. "Anymore" and "any more" are two entirely different parts of speech. "Anymore" is an adverb, plain and simple. "Any more" is an adjectival phrase governed by an adverb.

"I haven't found any mushrooms" means I never did. "I haven't found any more mushrooms" means I found some once, recently, but haven't found any since, though I keep looking. "I don't find mushrooms anymore" means either I'm not looking for them or the last time I looked was long, long ago. "I find mushrooms anymore" is outside my speech patterns.