Interesting... In the link below by snowflake, the seller states 1981. I first thought it could be a typo (for 1881, as stated on coin) BUT, she also has 1981 in the title. I would email her and see if she has history. Could have been a commemorative coin celebrating 100 years of his first inauguration. That would be my first stop.... If produced in 1981, there should be a bunch on the net.
I'm sure you know from your research there were countless coins, ribbons, pamphlets, etc. produce to memorialize Lincoln in the years following his death. Finding the maker might prove daunting.... but I don't blame you for wanting to know!