Edging is a way to keep grass from growing into garden borders and beds, but it also should blend with the landscape. Stone meets both criteria. It is attractive, comes in dozens of styles and is easy to install. Although stone takes a bit more time and maintenance than brick, it can enhance landscapes of many rustic or historic homes. If you or a neighbor has an old flagstone walk that needs replacing, it can even be inexpensive.
Measure how many linear feet you'll need and convert it into the number of cast stones or field stones you'll need using an average stone size. Real field or other stone may be sold by weight and varying density makes figuring volume complex. Tell the yard owner the dimensions you want to edge in and she'll be able to convert area to weight for her products.
Dig a trench around the border or bed, making a straight vertical cut through the grass. The trench should be about 4 inches deep and an inch wider than your widest stones. Spread the tarp out to hold tools, supplies and stone.
Lay strips of landscape cloth against the vertical wall of the trench and across the bottom section. Since the purpose of the cloth is to stop grass rhizomes and stolons from spreading, no cloth is needed on the garden side.
Fill the trench with about 3 inches of clean sand. Figure how many cubic feet of sand you need by multiplying the length of the trench times its width times its depth. If stones are formed, begin laying them into the sand; if they are irregular, arrange them on a tarp and fit pieces together so the outer edge is as straight as possible and stones fit together with little space between them.
Work stones into the bed to level the edging. Sink each an inch or two into the sand so it sits firmly in place. Tap individual stones into the bed or use a wide board as a guide to tamp together engineered stones that fit together. Once all the stones have been arranged, trim any exposed landscape fabric and fill spaces between stone with sand to support them. Water well and check that all of the stones are sitting correctly. If they aren't, adjust them, backfill sand and water again.