Help with mark: HB inside of a circle ( most likely German)

[MK]

I have two objects with the same hallmark; HB in a circle. One is on a plaque that is very similar to the type produced by WMF and the other on a circular plaque that might have been used for some type of trophy. The circular trophy also has hallmarks on the back that I have included on the second photo. Any assistance with this hallmark would be greatly appreciated.