The Mithril Coin is an artifact in the possession of Erin Solstice. It is a medaillon made of Mithril.
The palm-sized coin looked to be made of an odd metal, quite distinctly not silver but of a pale and reflective metal. It is light as a feather despite the size.
Originally, there was some sort of inscription on the coin, a rough border on both sides with faded imagery and possibly words, but all of that pattern was long gone and only the metal remained. The delicate engravings of letters and sigils on the coin were only faintly visible as the coin was covered in dust and the outer layer had bonded with other stuff over the centuries - this effect is called a patina, here possibly connected with wear. From the description it can be concluded that the "coin" is not actually a coin (which has to be usable as currency) but a medallion, due to its size, inscription and lack of nominal value.
After partial restoration, the artifact showed symbols of an old empire or nation with a sun rising behind a shining city. Around the rim of the coin were the shining words: Tamaroth, Who Leads. The G— of Rulers. Protect Us in Our Weakness.
At the Winter Solstice of the year of Erin's arrival in Innworld, three mysterious travelers entered The Wandering Inn and emptied her food storages completely while Erin cooked for them - none of the Inn's other guests noticed anything. The food they consumed was estimated by Lyonette to be enough to feed all the guests for some days. The mysterious strangers - one of them known by the name Tamaroth - offered Erin three gifts, each of them artifacts of unheard power, in exchange for her soul. Erin declined the offer and the guests left. Cleaning up their table, Erin found a single, odd coin that they seemed to have left as a form of payment. Erin only dimly remembered how she got the coin, but realized that it was special and thus kept it with her.
Some time later, when Erin met a Dwarf for the first time, she asked Dawil about the coin. While Dawil protested not to be a [Blacksmith], he could reveal to her that the coin was made of Mithril. He called it “worthless or priceless”, announcing that it had no real value except as a collector’s item. After that identification, Erin started to clean it with water and cloth but eventually didn't dare to scratch the coin's patina.
Months later again, Erin commissioned Pelt to restore the coin for her, as he promised to be able to make all the inscriptions visible again. Like Dawil, he protested for not being a [Historian] so couldn't identify it. However, he noticed that Mithril shouldn't wear like it had on the coin, which indicated further how ancient it must be. As Erin returned to him a few days later, Pelt had partially reforged the coin but had been struck with a life-threatening attack when he tried to restore the word "G—". Pelt claimed that the incident was just an accident and proof that he needed a more quiet place to work. Erin felt the coin burn in her pocket and made a remark about Dead Gods, suspecting no accident whatsoever.