Glowcaps are a traditional currency among sporelings, which can be found all over Zangarmarsh. They appear as large red glowing mushrooms. They are used to buy the reputation rewards from Mycah, the Sporeggar Quartermaster, once you become neutral to the Sporeggar.
Besides on the ground players will also receive a Glowcap when they complete one of the following quests:
Glowcap as a quest objective
Each quest turnin is worth 750 reputation and the quest is repeatable until 2999/3000 neutral.