Hello,
i stumbled on this one:

Russian Empire, Czar Alexander II (1855-81), Ekatrinburg mint, 1860 AD.,
1 Kopek (23 mm / 4,78 g), mintage ? , edge plain,
Obv.: A / II , A -monogram surmounted by a crown, within it the letter-numeral II.
Rev.: КОПҌЙКА / 1860. / E.M. , value in Cyrillic letters surmounted by a crown, date and mintmark below. (re-engraving traces at the 60 ?)
KM Y 3.1 (unlisted year for this type with plain edge) .
There is no visible trace of a toothed edge. The last year for this Ekatrinburg mint plain edge type according Krause is 1859.
Maybe my Krause is outdated, incomplete or wrong and a Russia expert will know more?
Regards