I’ve been searching online catalogues and I think these are Estonian, but I’m not sure. I think the one with the overprint might be from when the Russians became involved in Estonia in 1920? Not sure. I read up on Estonian history on Wikipedia. It is complicated. If anyone could tell me anything about these stamps or suggest where I might find more information, they would be a great help!
My Scott catalog shows an image of stamps with this style under both Finland and Russia, but the Finland issues have a different inscription under the central lozenge thing (3 Cyrillic characters, a number, and "Pen."; presumably a description of the denomination?) Finnish denominations for this design are 2p (Scott #64), 5p (#65), and 20p (#67) in the 1901 release on chalky paper, and then in a regular paper release, the same denominations again: 2p (#70), 5p (#71), and 20p (#73).
Finland #46 is a 1k denomination with orange-yellow ink with a very similar design (and the words under the central design match), but there are little dot-in-circle designs around the central lozenge.
In the Russia section, there's #46 which looks the same as the picture to me; it's the example stamp for this design in my 2010 Scott catalog, and the catalog image is in color.
Russia #49 is 5k and the ink is described in the catalog as red-violet. The 5p Finland stamps above are all green.
Russia #50 is a 7k denomination, and is dark blue. There is a Finnish stamp (#50) which is 7k, but again, it has the little dot-in-circle designs around the central part of the stamp.
The overprint looks like Russia Scott 220.
The next three look like Russia 76, Russia 41 or 57C (paper differences & perfs), and Russia 64 or 83 (paper and perf differences).
And thanks to StampCollector and dollhaus for pointing out that there are Finnish stamps that look like these Russian stamps! I looked through the stamps that I had initially categorized as Imperial Russia and found 2 that are definitely Finnish.
