The U.S. elementary school view of pilgrims wasn't quite accurate. The early American settlers basically had no clue what they were getting into the moment they stepped on a boat to cross the Atlantic, and the years after their arrival were not a pleasant idyll of farming and housekeeping.
Archaeologists and historians have long known about the "Starving Time" that occurred during the winter of 1609-10, as colonists recorded eating cats, rats, leather boots and yes, even the flesh of corpses. But until recently, there was no physical evidence that cannibalism had really taken place.
In 2013, archaeologists came upon a deposit of bones and found human skeletal remains mixed in with those of other animals. After analyzing part of the skull, they were able to determine that the female (around 14 years old) had some telltale marks that indicated someone was butchering the body for flesh or to access the brain for consumption [source: Stromberg].
The Smithsonian forensic anthropologist who analyzed the finding doesn't suspect foul play in the case, although it does appear that more than one person took part in the butchering, due to different markings on various parts of the body. Whatever the case, this was almost certainly due to the desperation of the time, and anthropologists are fairly certain that there are more cannibalized bodies waiting to be discovered in the Jamestown debris.