Several, large. circular features have been found in the Harney Basin, South East corner of Oregon.  The features are quite large and several circular features can be seen.  The most prominent feature is over 800 feet wide and contains five concentric rings. 

Underwater linear features off the coast of Cuba.

Carolina Bays are considered anomalies by many scientists.  The formation or cause of these oval, circular features has yet to be determined.

Underwater patterns off shore of Marathon in the Florida Keys visible for over 6 square miles.

Linear, underwater anomalies that can be seen on the Google Earth topographic data of the surface of the sea-floor.

Circular, oblong features aligned in rows off the Southern tip of Florida within the Florida Everglades.