She is sometimes listed as Wickham Boyd, Boyd being her married name. She was born in 1930 and died in 2009.
Her parents were named Magaw and I've found no previous record of a marriage under Wickham. The plate, like much of her work is from central Vermont. It is approximately 10 1/2" square and is approximately 5/8" tall.
The center is depressed, the edges rise to the rim. Done in a sgrafitto style in dark blue on black. The underside is a brownish color. I recommend this only be used for decorative purposes. I believe is a raku fired.
The item "Vintage Mid Century Modern Sgraffito Studio Plate Signed Nancy Wickham Listed Ar" is in sale since Saturday, December 14, 2019. This item is in the category "Pottery & Glass\Pottery & China\Art Pottery\Studio/ Handcrafted Pottery".
The seller is "jp1wol2" and is located in Saint Johnsbury, Vermont. This item can be shipped to United States.