The design for a lie-flat mattress pad, as shown and described.
FIG. 1 is a front view of the mattress pad showing the new design, lying flat.
FIG. 2 is a detail of the bottom corner of the front view of the mattress pad depicted in FIG. 1.
FIG. 3 is a back view of the mattress pad of FIG. 1, lying flat.
FIG. 4 is a detail of the top corner of the back view of the mattress pad depicted in FIG. 3.
FIG. 5 is a perspective view of the mattress pad depicted in FIG. 1, partially rolled up.
FIG. 6 is a detail of the back side of the mattress pad depicted in FIG. 5.
FIG. 7 is a left side view of the mattress pad depicted in FIG. 1, rolled-up; and,
FIG. 8 is a left side view of the mattress pad depicted in FIG. 1, rolled-up and contained within the pocket.
A view of the right side has been omitted since the right side view is identical to the left side view.
Broken lines shown in the drawings are for the purpose of illustrating environmental structure or to define boundaries and form no part of the claimed design.