I have a Garmin eTrex Legend ( cheap ) that will mark a waypoint, but is too complicated to use while combining at the same time. I would also be intersted to know if there are other handhelds that would work easier.

Sometimes when my mind wanders off, I wonder why they haven't made a device that will detect a stone in the field much like a fishfinder would show fish in the water. If the device could then record and map the stones using GPS coordinates. Then when it's pickin time, just print out a map a go fishing ( for rocks that is ).

This device would also be used as a warning for when you are harvesting or working the field. Would save a lot of repairs.