What shape are they? I saw a lovely one where they had cut through the middle of round or oval? ones and sewed the raw edges into the center seam of the block. They then button hole stitched the outside edges down to the background and they formed crocheted heart shapes. I think you would need oval ones to get the heart shape? If they are round, they would make a lovely scalloped border if you sewed halves into the seam and then stitched the doily halves down to the wide border.