I have been looking around for something Nazi-related that fits the dimensions of this plate and come back empty handed. My guess is that it dates to the turn of the century and in this case simply signified "good luck," the original connotation of the swastika. The "history of the swastika" website has some good details. Either way, keep it in your junk box for future re-evaluation. Back when I started detecting, I started what I have termed "the greater junk box" and "the lesser junk box." (These names have now come to signify several boxes each!) Back then I didn't know what most of the stuff I recovered was, but since then I have realized that I had several good finds rolling around in the junk boxes. These have included valuable tokens, an early Red Cross lapel pin, and a Civil War knapsack hook. Ya never know. In some cases ya never will, but there's always a chance. From personal experience, you should keep a record of where you found it and what you found it with for future reference. I didn't find the Civil War relic mentioned above at a Civil War site, but I can't remember where I found it. (Frustrating!) Best of luck.
Buckleboy