"USA" marking, "K#" only clues. I need help :)

Hello, I am new to this forum...I've been collecting glass and ceramics/pottery for years but mostly pieces I recognize (and of course like). I have a small collection of Italian glass and pottery and some american glass.

I have had these three pieces for some time now and have displayed them in previous homes but have no place for them here in our current house. They have been in storage for over 6 years and I think it is time to send them on their way. They were purchased on three different occasions at three different places here is the great lakes region. The only markings are "usa" and then a "K" with a number following. Three pieces, three different numbers. I would like to at least know who made them so I can determine the best way to rid myself of them.

Any help is greatly appreciated...

are you sure it's USA ? it looks like OSA to me which would /could be OSA keramik Helsingore Denmark ,Ed

Yes unfortunatly. It is definately U.S.A. and then K#. The image does look like an O but in person there is no mistaking it. Thanks for the reply...