Put on a dust mask over your nose and mouth. Put on a pair of safety glasses. Sawing generates a lot of sawdust. Wear safety gear to protect your eyes and lungs.
Lay a sheet of untreated lumber flat on the ground. The lumber should be 1 inch thick and at least 5 feet long on the longest side. The longest side of the lumber will be the length of the stakes.
Measure and mark sections 2 or 3 inches wide across the width of the lumber sheet with a carpenter's pencil. The lines marking the sections should be parallel to the longest side of the lumber sheet. Make the lines down the length of the whole sheet.
Lay the sheet of lumber across two sawhorses. The longest side of the lumber sheet should overhang the sawhorses on one side enough so that the circular saw can pass without cutting the sawhorses.
Cut along the first parallel line with the circular saw. Now you have your first stake, which should be 2 or 3 inches wide, 1 inch thick and as long as the longest side of the lumber sheet.
Move the lumber sheet a few inches to make sure it overhangs the sawhorses and cut along the second line to make another stake. Continue moving the sheet and cutting along each parallel pencil line until you have cut stakes from the whole sheet.
Cut the stakes to a length of 5 or 6 feet if they are longer than this. Now the stakes are ready to use.