I discovered recently that rare mushrooms are not like Jacob's Ladders in terms of how many can be spawned in your town based upon how many are already placed in your town! Jacob's Ladders do not spawn naturally with x many (14 I think?) are already planted, but rare mushrooms do not seem to have that issue because I have like 20+ being used for landscaping and I keep getting them! Also, another neat fact about rare mushrooms is they do not negatively affect your town's perfect status even though they came from the ground like fossils/pitfalls/gyroids because the game recognizes it like any other mushroom which makes logical sense, but still cool though nonetheless!
Oh my god no wonder I haven’t seen any more Jacob ladders spawning. I have yet to come across a rare mushroom though. I’ve only come across maybe 2-3 in all my years of playing this game.
I recently found out that wilted perfect fruit trees do not negatively affect your perfect town status. I have tons in my town because I’m making a spooky forest but I guess it just counts as a regular tree.