Check this mattress pad from Bed Bath & Beyond. It comes in special sizes:

With luxurious cotton comfort and Pure Sleep antimicrobial treatment, this mattress pad will take your bed from ordinary to extraordinary. A great way to protect your mattress with an attractive dobby pattern. The patented Vertical Stretch Tailor Fit skirt fits mattresses up to 20″. 100% cotton pad has a 300 thread count and 12 ounces of polyester fiber fill.

Sizes:

Twin 38″ W x 75″ L;
Twin Extra Long 39″ W x 80″ L;
Full 53″ W x 75″ L;
Full Extra Long 54″ W x 80″ L;
Queen 60″ W x 80″ L;
Olympic Queen 66″ W x 80″ L;
King 78″ W x 80″ L;
California King 72″ W x 84″ L.

Five-year warranty. Machine wash. Made in the USA.