Well, I’ll copy out some of what I have here, and give you some links. I haven’t got a central resource you can check out, though.
So:
Inscriptions on gold: the Orphic religious movement in ancient Greece started to become prominent around the 7th century BC. Members were buried with ritual writings inscribed on gold plates. (Griggs, “The BoM as an ancient book,” Book of Mormon Authorship, ed. Reynolds.)
burying metal plates: In 1933, "German archaeologist Ernst Herzfeld discovered in Persepolis that ‘two shallow, neatly made stone boxes with [sealed] lids, each containing two square plates of gold and silver, had been sunk into the bedrock beneath the walls at the corners of…the apadana’ (columned hall of the palace). These plates ‘were laid down, probably in the presence of Darius, in 516-515 BC…’ (Ernst Herzfeld, in translation from the German, cited in Echoes and evidences of the BoM Parry ed.)
Since that discovery, another pair has been found saying “Palace of Assurnasirpal…” and another gold tablet in Sumerian Umma was found in 1937. (Nibley, An approach to the BoM)
You may be familiar with the Dead Sea Scrolls, which included one scroll of copper. Ancient writings on metal have also been found in India and even heard of in in Mesoamerica; non-LDS scholars have collected stories of Mayans and others who claimed that their histories had been inscribed on gold and hidden.
This short article touches upon the discovery in the 1980’s of two small silver scrolls at a Jerusalem dig. Apparently the inscriptions are Biblical and now constitute the earliest existing copy of a Biblical text. The scrolls date from just before the Babylonian captivity.
Here is a short article from 1979 which is a print transcription of an article that showed photos of different ancient metal texts. The descriptions are there, but not the photos.
Anyway, I hope that partial picture gives you an idea. Since I’m not really into all this stuff, I can only supply a patchy and incomplete list from what I’ve picked up here and there. But it seems to me that anyone could look up these discoveries. It appears that writing on metal occured to several different ancient peoples.