O Happy Day was created by Timna Tarr paying attention only to background fabrics, letting the circles fall as they may.

Timna made O Happy Day when her kid was little so she didn't have time to sit at the sewing machine. As a result, she could carry it around with her and work on it and appliqué on the go whenever she was at her child's activities or had some free time. It changed the way she looked at and worked on quilts because she laid the blocks out only looking at the background fabrics, not the circles. So she laid the quilt out with only the backgrounds in mind and wherever the circles landed they just landed.