Never mind to my question ... That farmer's quest seemed to be the best way.
I swear, though, that Farmer's either running the biggest scam, or he's the biggest *******.
Either he's faking it, to get the players to clean his weeds, so he doesn't have to.
Or, every time you give him the pitchfork he just lobs it back out into the field, to make you fetch it
again.
Oh, or the creepy weeds secrete some psychotropic compound which has him convinced that his pitchfork is out there.
You go out looking for it, rummaging in the weeds, you become convinced you've found it.
You return it to him, but there never was a pitchfork, and the cycle of delusion begins anew.