Cut a shelf overlay. This is a strip of fabric the length of your blocks and the depth of your shelf. Stitch your overlay to the top of your blocks along one long edge with right sides together. Now you have two rows sewn together. One is the overlay, the other the quilt blocks.
Machine stitch around almost entire piece.
Trim corners, batting and excess fabric away. Turn right side out and push out corners carefully. Quilt your blocks or leave as is. Machine stitch in the seam between blocks and overlay. This will help your blocks to hang straight and even.