best suggestion is to first know what she means by "white"
Back in the late 70's a quiltr made all her projects and designs in patchwork with unbleached muslin. So you can do traditional patchwork and just use one color. Quilting then adds other design and texture. So don't discount patchwork all in white. or perhaps tone on tone white.
Then there are preprinted wholecloth in white and just slightly off white available. These are printed in a washout ink. So best to find our exactly what she means before even considering any further.