Commercial (less expensive) GPSRs typically have an error range of up to 10 meters. It makes Geocaching interesting. More expensive models that use extra satellites have smaller error ranges. The problem is that the error range drifts. One time it might be to the NW, another to the south.

Typically, you can make a decent crop circle with pegs, ropes, and boards. Add some planning and pre-build diagramming, and you're golden.

Fred

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"For shame, gentlemen, pack your evidence a little better against another time."
-- John Dryden, "The Vindication of The Duke of Guise" 1684