Mushroom

That's just the fruiting body of the organism. think of it like a flower on a bush. plucking the flower is not going to do much, the fungal body is still in the soil. aka the Mycelium It can be beneficial to the plant and it can not be depends on the mushroom, I don't like them as they release more spores into the environment and I don't need that in my weed or more of it in my indoor air quality. Just pinch or pluck it out. Its not "magical" so don't eat it. and when you start to fertilizer more, the mushroom body in the soil will die back and stop growing as they do not like fertilizers. Best to get it before the cap opens to release the spores. They do not give off enough CO2 to make any difference. even the mushroom bags for CO2 are crap for that and its a whole Colony of em.