I'm no expert but maybe you could do an on point square inside the brown stars; echo around the stars, and then stitch in the ditch around the brown star squares. For the white squares maybe using brown thread, quilt a star shape to match the brown stars and then follow that in white or cream thread and repeat the same sequince you did in the brown star squares - the on point square, the echo around stars, and stitch in the ditch around the whole square.