Cut the grass to a height of about 4 inches throughout the area from which sod will be cut. Remove the grass clippings and other debris to leave only the living sod.
Hammer two pegs into the ground, one at each end of the first strip of sod. Attach a length of string between the pegs to form a straight line. Place a second pair of pegs 12 inches to one side of the original pair and attach a string between them. The result is two parallel lines of string, 12 inches apart. Add further parallel lines until sufficient strips of sod have been marked out on the ground.
Remove the soil to a depth about 5 inches along the unused edge of the first line. Create sufficient space to be able to cut under the first line of sod parallel to, and 4 inches below, the surface.
Cut vertically into the ground along each string line, to a depth of 4 inches, using a straight spade. Every 2 feet, cut a line across the sod from one string line to the next to divide the strip into 2 feet long slices. The result is a strip of sod 12-inches wide subdivided into rectangles 2 feet long.
Undercut each rectangle 4 inches below the surface and lift the "brick" out of the ground. The result is a sod brick 12-inches wide, 2-feet long and 4-inches thick.