Start by rounding the corners of the placemat. I do this by tracing something circle shaped (like a cup or ribbon package) with a fabric marker.
Iron one short edge of the pocket down 1 inch and the other edges about 1/4 inch
Sew across the 1 inch side.
Pin each pocket in place on the front side of the placemats.
Fold the ribbon in half and place the folded edge on the opposite side of the pocket having the tails face inward and a small bit of the folded edge sticking over the edge.
Put a back piece of the pocket right side down so the two pieces should be right sides together and the ribbon is sandwiched between the two pieces of fabric.
Sew around the edges leaving a 5/8 inch seam allowance and a small opening to flip the placemats.
Flip the placemat right side out. I like to use a loop turner for this task.
Iron tucking the hole in and then top stitch around closing up the opening as you go.