The Buried Giant

A great stone face rises from the forest floor. A nose as tall as a man, eyes the size of a child's large ball. A giant head has thrust itself up through soil and decaying foliage. Its forehead is covered in a carpet of thick moss, small plants and flowers from from its ears, ferns make it a green toupe.

Possibilites:

A Slumbering Titan: Buried in the earth long ago, an elder stone giant is still sleeping. He will be waking up soon, and when he does, he will rise completely from the earth, and he will be hungry from his ancient slumber.

Failed Sorcery: A Mage attempted to create a giant golem from raw earth. He failed, but is working on research to complete the spell. He will return soon, the head is just the top of the creature that is half formed in the earth.

Into the Mouth: The Head's mouth is open, and is a stairway that leads down into a previously unknown dungeon. It is magical in nature, and the only way to reach the extradimensional dungeon is by going in through the stone mouth. Let the digging commence

Red Herring: The head was carved many years ago by a local artist. He would take several bottles of booze and his chisels out into the forest where he found a boulder. After a few years of weekend benders, he had the head sculpted. A hundred yards away there is another boulder carved like a hand coming out of the earth. The artist is still around, still drinking, and likely considered a local degenerate.