You can certainly say it - it conjures a great image! I would say 2 things though...
1) You could make it a little more specific i.e. mushrooms don't always grow after rain. Perhaps "wild mushrooms" would emphasise your point, but I may just be in a picky mood after looking at it too closely!
2) What is the context? If this is in an academic assignment, I'd suggest being careful with language that's too poetic - for no other reason than it gets noticed as being unexpected / distinct (and unexpected forms are often called inappropriate by teachers)! This can be a shame, but on the other hand, using personal and markedly creative language can seem to be trying to convince emotively rather than logically / factually (the 'academic way'). Oddly, people would normally accept "the sound/rumble of dissenting voices had been growing/rising since..." even thought it is also figurative - it just conforms to what people expect in this kind of writing! I remember that I wasn't even allowed to write "like" in assignments, let alone full similes!
In short, if it is for an assignment, rephrase it in a more boring way and save it for your novel! You can certainly use it in English though.
Student or Learner