You will need:
1/4 yard each of 7 light fabrics – 1/4 yard each of 7 medium fabrics – 1/4 yard each of 7 dark fabrics.
To make it more coordinated I picked 7 colors then used a 4th yard of each shade. For example I used a dark, medium and light blue, dark, medium and light green, etc. I have used the purple and green colors for my samples.
If you buy a half yard you can make a much larger quilt. Mine covered the top of my queen mattress prior to the borders using only 4 inches more of each than the quarter yard.