The phrase "a flat patch of" is correct and usable in written English.
It can be used to describe a specific area that is level and even, often in relation to land or surfaces.
Example: "The hikers found a flat patch of ground to set up their tents for the night."
Alternatives: "an even area of" or "a level section of".
Salmon patch (nevus simplex) is a flat patch of pink or red skin, often small, usually with poorly defined borders.
Splayed against a flat patch of green inscribed with leaves, she is half truck driver, half Matisse mademoiselle.
Port-wine stain (nevus flammeus) is a flat patch of purple or dark red skin, often large, usually with well-defined borders.
Here and there, in these evacuated landscapes, a flat patch of white doubles as both water and sky, twisting perspective and baffling the eye.
Cabnet led the cast to a flat patch of spotty grass, just south of the Sheep Meadow, and drew end-zone lines in the dirt.
There, the baby was set down on a flat patch of ground while the prayerful removed their shoes and faced West.
Or Royal Liverpool, to give it its proper name,, a small, flat patch of links on the north-west tip of the Wirral peninsula.
We trace a man-made river back to the RotorWay factory and set straight down softly on a small flat patch of driveway in suburban Arizona.
Sitting on a large flat patch of dry ground, the sprawling camp is currently home to 347 families, including 1,095 children.
It often starts as a slowly enlarging flat patch of discolored skin and is sometimes mistaken for a stain.
A short distance from the Singh family home this past week, on the one large flat patch of ground near the village that is not being tilled for crops, about two dozen men shifted bricks and sand, wreathed in fog while a backhoe rumbled.
