Mort myre fungi can be obtained in Mort Myre Swamp by casting Bloom with a Blessed Silver Sickle near some dead logs which may or may not grow the fungi.
Each cast of the Bloom will drain a few prayer points from the player, with a maximum of 6. The amount drained is completely random and not dependent of the player’s prayer level. Prayer drain is not affected by how many items are actually made. The Blessed Silver Sickle can only be obtained during and after completion of the Nature Spirit quest.
All the harvests, including the fungi, can be used to fill a Druid pouch, which makes Ghasts visible and attackable. The fungus is equivalent to 1 harvest when filling the Druid pouch. Mort Myre fungus can also be used to make Super energy potions in the Herblore skill.
Collecting Mort myre fungi to sell is an effective way of making money.