(Inspired by a post on the Language Log blog.)
Cutter Stalks are a variety of deadly corn with razor-sharp leaves. Walking through a field of cutter stalks does 1 point of damage every 30 feet of distance covered, if the traveler has any exposed skin at all. Leather armor reduces this to 1 point for every 120 feet of distance and will damage the armor. Metal armor gives complete protection, but only if the wearer is completely encases.
Walking through a field of cutter stalks that has been substantially damaged (whirlwind, wildfire, hail storm) leaves some sharp-edged leaves intact, but substantially reduces the risk: travelers take damage only on a 5+ on 1d6.