My grandfather Ray Dukeminier grew up in the Texas/New Mexico area and was a champion fiddle player. I remember the family getting together at my grandparents house and nearly everybody playing some sort of instrument as they had a jam-session or "hoedown". Amoung the songs that were sung during those howdowns as well as times where Grandpa would play his fiddle and sing alone was a tune that has been discussed here. Although I'm sure that I have some lyrics wrong since this is a childhood memory I believe it is mostly correct.
Interestingly enough, however, I have not seen on this blog the number being three nor what those folks in the cornfield had in their possession or what they were doing.

This is what I remember:

Some people say that a Preacher don't steal,
But I caught three in my cornfield.
One had an axe and one had a bell,
The other little preacher was a runnin' like hell.
Say to Moses - whatcha doin'? I'm agoin' on, I'm agoin' on, I'm agoin' on
Say to Moses - whatcha doin'? I'm agoin' on, I'm agoin' on, I'm agoin' on