When most people think of T-Shirt Quilts, they think of the kind of T-Shirt Quilt made with all the logos, pictures, and "interesting" stuff from favorite T-Shirts.
When I make a T-Shirt Quilt, I'm usually using smallish squares cut from the solid-colored "plain" parts of T-shirts.
Here's one of the latest ... Just before quilting. I quilted it with variegated thread, and the rainbow-colored thread was just the thing for this quilt.
The colorful squares in this quilt were all cut from actual T-shirts, and the white squares were all cut from a cotton jersey-knit sheet.