From Middle English surfeite, surfet, a borrowing from Anglo-Norman surfet, surfeit and Old French sorfet, sorfait, past participle of surfaire (“to augment, exaggerate, exceed”), from sur- (“over”) + faire (“to do”) . A surfeit of wheat is driving down the price.

surfeit (n.) early 14c., "excess quantity;" late 14c., "overindulgence," from Old French sorfet "excess; arrogance" (Modern French surfait ), noun use of past participle of surfaire "overdo," from sur- "over" (see sur- (1)) + faire "do," from Latin facere "to make, do" (from PIE root *dhe- "to set, put").