Bone harvesting system including methods and devices for obtaining and/or removing osseous debris from a bone using an auger having a flexible, helical fin projecting from a shaft. In an exemplary method, a leading end region of the auger is placed into a reamed portion of a bone's medullary cavity via an entry site extending into the bone. Osseous debris is driven toward the entry site with the auger. At least a portion of the osseous debris that has passed through the entry site is collected outside the bone. In some embodiments, the leading end region of the auger is deformed by contact between the helical fin and a wall of the medullary cavity, to conform the helical fin in the leading end region to a portion of the medullary cavity.