Help identifying the markings on this silver(?) plate

[lakes10kfun]

I am trying to figure out who made this silver (?) plate and how old it might be. The pictures are of the Markings on the back of the plate and the entire front plate. I looked at all the marks on the Silverplate Marks page but had no luck finding this one. Thanks in advance for your help.

[Traintime]

Sheriden Silver Company here : https://www.925-1000.com/silverplate_S2.html

[lakes10kfun]

Thanks again Traintime!