Whit cotton fabric is the best choice for cushions. Buy white poplin and cut four pieces each measuring 10" * 10". The finished cushion will measure 9 1/2". The extra 1/2" goes for the seams.
Keeping two pieces right sides facing each other, stitch along the edge with a 1/4" seam.
Leave a gap of 4" on one side for inverting and stuffing.
Cut the corners for sharp finishing. Be careful not to snip the seam.
Invert the fabric inside out through the opening. Use a sharp pencil to make sharp corners.
Stuff the cushion with synthetic cotton filling. Start from the lowest part and fill it tightly to get a neat finish.
The finished cushion looks like this.
Thread a needle. Knot it up. Start form one side of the opening. Insert the needle from inside to out on one side.
Now insert it on the other side inside out.
Continue this zig zag stitch until you come to the other side of the opening.
Pull the thread to close the opening. Finish with a knot.
The cushion is now ready.