To increase in number suddenly and rapidly (as mushrooms often do). Even though I'm constantly tending to my garden, the weeds just spring up like mushrooms nonetheless. I thought I only had a transmission problem, but other issues with the car are now springing up like mushrooms.

Very quickly and in great quantities. Used in reference to things or people appearing or multiplying. As the economy recovered and jobs became more plentiful, high-rise apartments started popping up like mushrooms to accommodate the huge influx of worker pouring into the city. Self-professed writers started appearing like mushrooms with the advent of the blog.

Psilocybin mushrooms, which have psychoactive effects when ingested. I ate way too many psychedelic mushrooms and had the trippiest night of my life! They told me these were psychedelic mushrooms, but I don't really feel anything after eating them.

Psilocybin mushrooms, which have psychoactive effects when ingested. I ate way too many magic mushrooms and had the trippiest night of my life! They told me these were magic mushrooms, but I don't really feel anything after eating them.

To increase, expand, or grow into something much larger in size, scope, or scale than something was initially, especially in a short space of time. We started out as a small mom-and-pop shop, but the business mushroomed into a huge nationwide chain in just a few years! What was a minor talking point during the beginning of his campaign has mushroomed into one of the key issues of this election.

Psilocybin mushrooms, which have psychoactive effects when ingested. I ate way too many sacred mushrooms and had the trippiest night of my life! They told me these were sacred mushrooms, but I don't really feel anything after eating them.