I found a few of these chairs, and the only mark I can find is from International Designers Group. According to this prior discussion http://www.designaddict.com/forum/General-discussion/International-Desig... , it seems IDG was a US importer from various countries and designers in Europe in the 50's, 60's which fits the condition of these chairs. They would apparently want only their own badge on their furniture, so original makers marks are absent, making identification more difficult than usual. At first I thought they had leather seats, then I realized it was old naugahyde, then I saw that the original green fabric is still on them, though I haven't taken the naugahyde off to see what condition it is in.
So can anyone recognize these chairs? Thank you as always!