Sorry to hear that, hope you'll get well soon
The only online-info I have found is
thisIt's about soviet and russian coins after 1991. If you need more help with these ask me and I'll do my best.
There might be some variants in the coins of the middle 70's, because during that time they redesigned the coat of arms. I am not sure about the exact change-date since my date-collection is not filled yet. Perhaps the Conros catalogue of soviet coins would know more. It costs about 5 euros on german eBay. I haven't got one yet, only the 1700-1917 one.
The 10 kopek
1990 without mintmark is very common and I have never seen one with a mintmark and I think there must be a mistake in Krause. 10 Kopek
1991 without mintmark (1990-obverse) is quite rare and sells for about 2 euros. Krause has very weird listings about the soviet coins 1990-1991.
I have encountered* these:
1 Kop: 1990, 1991L, 1991M
2 Kop: 1990, 1991 L, 1991M
3 Kop: 1990, 1991L, 1991M
5 Kop: 1990, 1991L, 1991M
10 Kop: 1990, 1991, 1991L, 1991M, 1991M"II"
15 Kop: 1990, 1991L, 1991M
20 Kop: 1990, 1991L, 1991M
50 Kop: 1990, 1991L, 1991M, 1991L"II"
1 Rbl: 1990, 1991L, 1991M, 1991LMD
5 Rbl: 1991LMD, 1991MMD
10 Rbl: 1991LMD, 1991MMD
15, 20 and 50 kopeks 1965-1977 are quite hard to find too.
I hope you find some of the better dates
*"I have encountered" doesn't necessarily mean the same as "I own"