Messenger of Allah ﷺ said, "The Kam'a (i.e. a kind of edible fungus) is like the Manna (in that it is obtained without effort) and its water is a (medicine) cure for eye trouble."  

قَالَ رَسُولُ اللَّهِ ﷺ الْكَمْأَةُ مِنَ الْمَنِّ وَمَاؤُهَا شِفَاءٌ لِلْعَيْنِ