In Poland it's known as "podgrzybek brunatny".
Yeah, I read it in Polish wiki. :) Brunatny=brown?
Why do you call it Polish mushroom?
I'm not sure about the ethimology. That probably somehow related to to Poles who lived in Russia... or maybe there's a belief that it was firstly brought from Poland. Another name of it "Pansky grib", as you see there's also trace of Poland in this name. :)
Some people call it also "dubovik" (dub=oak-tree), but that's wrong. Dubovik is what pawian posted above:
It happens that during holidays that I spent in the mountains I consume large quantities of mountain borowik ceglastopory