19th century Central Pacific Railroad Chinese Camp Pottery

From: abbjo

I have a question about 19th century Central Pacific Railroad Chinese Camp Pottery. I have 4 pieces of pottery that have been in my family for years. Looking on your web site I have seen pictures that closely resemble 3 out of the 4 that I have. Is there someplace I can find out more information on these? Maybe what each was used for, and possibly a value?