An edging unit comprises a structure having opposed top and bottom surfaces, opposed first and second side surfaces extending between the opposed top and bottom surfaces, and opposed first and second end surfaces extending between the opposed top and bottom surfaces and between the first and second side surfaces. The top surface comprises at least one pair of opposed segments. Each pair of segments includes first and second segments respectively opposing one another with respect to a center of the edging unit. The first segment defines a first upward or downward slope between the first side surface and the second side surface and the second segment defines a second upward or downward slope between the first side surface and the second side surface generally opposite in direction to the first slope.