Vintage Milligan RP Pottery Stoneware Serving Chip and Dip Bowl Set Blue Speckle

Vintage Milligan RP Pottery Stoneware Serving Chip and Dip Bowl Set Blue Speckle I do not know who made this bowl set. It is marked Milligan with a backwards R and forward P. It could be Ron Milligan- the one hand potter or it could be Rockwood Pottery but the RP mark does not look exactly correct. If you have any ideas who made this beautiful piece, please, let me know. The large bowl is about 11.25" in diameter and 2" tall. The smaller bowl is about 4" in diameter and 2.25" tall. They are a blue and white colored with specks of brown and blue.  No chips or breaks. May have minor imperfections. See pictures as they are part of the description.