Farms. Some fields are more easily manages in circle rather than fully square edges
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specifically the irrigation systems are basically a long pipe on wheels that's fed from and pivots around the center of the circle exactly like the minute hand on a clock face.
This allows for very few moving parts and energy to keep the circle watered. You can hit those corners but the equipment is much more complicated so more difficult and costly to run.
Theyr'e the patterns made by field irrigators that rotate around a central point.
Farmers using rotating irrigation booms