Poczta Solidarność was a private Polish underground postal service, issuing a large number of cinderellas. I have no information whether these stamps have actually been used.
Several of the seriws had a heraldic character, showing mainly coats of arms of families.
I know of the following series, but I have no information on the year when these were issued. Any information is welcome !
The two following series have been issued in gold and silver and refer to courier services: