They are lovely. What kind of research have you done already if any?
To be honest I have no idea where to start with these. I have not seen anything similar. I would not know what to search under. There are no marks to go by and my knowledge in this area is very small!
According to my research Adventures of Huckleberry Finn by Mark Twain was first introduced in 1884.
The one cup looks like it has Tom Sawyer on it. It looks like milk glass or is it porcelain from the photos?
Possibly Victorian or till 1930s?
Now since you have my curiosity and I love research I will look some more.
Oh, how wonderful! Thank you so much. I think they are porcelain.
I really appreciate your effort. Thank you.