They are probably not in a good condition since they were laying in paper bags and boxes, but I'm still curious what they were used for since most of them don't look like regular post stamps... My research states that they were used as tax revenue?
Can anyone provide any further insight? Especially the last two where the orange one has a red overprint.
Most look like revenue stamps, not sure of the countr(ies), maybe Yugoslavia (sometimes spelled Jugoslavia), but the green ones are Yugoslavia 1950-51 series, Scott No. 346. Note that some of the text is Cyrillic ...
An Austria-Hungary revenue on the left; there were separate issues for each part. The orange stamp with red overprint on the right is again one of the Jugoslavian ones from the kingdom, with the overprint and arms changing the country name to the Federated Republic of Yugoslavia.
Good pictures, but please don't post from sites that require anything special to view. When downloaded, I got a hash of characters that looks like a steganographic hack.