This was about to be thrown away! So I took it home with me to find out anything about it.
I found out that it was made by Alphonse Cytere (1861-1941) at the Ecole de Nancy (of which he was a founding member circa 1925).
One of his "claims to fame" was to create a specific metal lustre on ceramics ... which became known as "grés flammes de Rambervillers".
This is one example of his lustre glazes.
The marks include a lozenge stamp which reads "UNIS FRANCE" - which stands for "Union Nationale Inter Syndicate".
Underneath is what appears to be squared prarenthese ""
And underneath that is Alphonse Cytere's signature stamp.