Mushroom is a Manga/Manhwa/Manhua in english language, Gore series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

At the end of the 90s, a group of biologists commissioned by a pharmaceutical company explore an island in the South Pacific to seek new genetic resources. However, our backpackers soon discover a terrifying massacre by an unknown entity…