The plate's decoration ｓtyle and shape do not look Chinese, and the mark or marking is defintely neither a Chinese or Japanese character proper. Just some potter's mark maybe.
This type of 3D effect in decoration is absent from pre-20th century Chinese art, with the exception of some made under the influence of Giuseppe Castiglione, a missionary and artist in China during the 18th century. But, I don't think this is what we see here.
Maybe you should look at Japanese or European decoration styles. There is also a chance that this is derived from Chinoiserie, European decoration which copied Chinese motifs to some degree.
If this plate is from the time you state it might have some value even if it is European. One thing that is notable is that the mark is hand made. European manufacturers rarely have hand made marks.
Hope this gives you some further help in your research. You could try to search Ebay listings for something similar or try some European marks site. If you find what it is, maybe you could drop me a note. I am always eager to learn something new!
