Hello, The second character is somewhat unclear. I wonder if it is a Japanese piece? If it is Japanese then the mark is pretty clear, but with a Chinese one it would be rare as a character is used that seldom was used this way, in the distant past.
My translation for the mark is "Made by Nishiura Pottery Shop", given that it is Japanese. "Nishiura" can be a family name as well as a place name.