I have several black and white crochet pieces in the house. I had been trying to create cowls with different yarns. One was going to be a ruffle cowl and the other was striped with black and white. I also created an open lace pattern with ruffle yarn. (You can see the individual pieces below.) I connected the pieces and added additional rows of black and white yarn. Some yarn had metallic in it and others had sequins.
The pieces that were already created were from bottom to top: The black metallic shell stitch to the ruffle was going to be a cowl. I decided to use it. I crocheted on top on it until I reached the end of the black and white shells. Then, I connected the white piece with the black and white stripes.
You can see the individual pieces below.