When Lin Feng plucked the Cloud Forest Tree, he retained an avatar of the Parasol Fairy on purpose. He was after the Celestial Spirit Snow Dew.
Although he had not personally witnessed the Parasol Fairy creating the Celestial Spirit Snow Dew before, the scent left behind after the creation of the Celestial Spirit Snow Dew was noticed by Lin Feng immediately. After checking with the system, he found out that it was a rare treasure.
It was very helpful for cultivators in the Immortal Soul Stage to break through their realm. It increased the probability of doing so by a lot.
Lin Feng would not let such a good thing go. When his mana encountered the avatar of the Parasol Fairy, which was the mushrooms, he immediately knew that the Parasol Fairy was the source of it. That was why he retained the avatar of the Parasol Fairy on purpose when he plucked the Cloud Forest Tree.