The Getty's fragments of a series of lead tablets from (it is thought) Selinunte, Sicily, have been edited, and papers from a 2010 colloquium published. See review:
http://www.bmcreview.org/2014/12/20141210.html
The text on the tablets consists of hexameter verses. Only some of them are intelligible. The verses are in the voice of a narrator, whose identity is not given in the surviving lines. He announces that he is [from here I paste from the review}
"uttering effective incantations (οὐκ ἀτέλεστ' ἐπ̣[α]ε̣ίδω̣). If written on lead and hidden in a 'house of stone',4 these words will offer effective protection, by land and by sea. There follows an address to Paiêôn, defined as "you who send averting charms (ἀλέξιμα φάρμακα) in every direction [or: averting of everything]" (l.6), who has uttered "immortal verses [or: words]" (ἔπε' ἀθάνατα) for mortals. These 'words' turn out to be a cryptic narrative, an historiola, describing how a child leads a she-goat, attendant of Demeter, with full udder "by force" (ἀνάγκη[ι]) from a dark mountain (ll.8-13). Apart from the introduction of Hekate of the Roadside, who shrieks barbarian utterances in a terrifying voice (ll.13f.), the remainder of the lines towards the end of Side A col. i give no coherent sense. The beginnings and endings of all the lines in col. ii require supplementation. A verse referring to "averting charms" has been restored to begin with a second reference to Paiêôn (l.23); he seems to be requested to help an army (?) and ships against deadly dangers, and possibly livestock and craftsmen (ll.25-28). The word πόλει can read in l.31. After another probable invocation of [Paiêôn] (l.32), there follow some virtually unintelligible lines mingling fragments of what in Imperial times were recognised as Ephesia grammata with isolated words that occur in the cryptic narrative (ll.33-42). The last lines, on the back of the set of four conjoining fragments (Side B), seem to refer, inter alios, to Herakles (Διὸς υἱός[---- ] (l.46), possibly Asklêpios or Artemis (…/ υἱω]νός τε Διὀς, l.47), and Phoibos Apollo (ibid.), followed by yet another appeal to [Paiêôn], identified by his ἀλέξιμα φάρμακα (ll.49f.)."
One of the editors is Dirk Obbink, who is also involved in the Sappho fragment from the mummy mask that has spurred controversy over provenance. The provenance of these tablets is unknown, as far as I know - came from a donor who got them from a dealer.
Jan Bremmer, an authority on Greek religion, by comparing the lacunate text with others, establishes its origin around Selinunte betw c. 430-409 BCE (the latter the date of the Carthaginian sack of the city). Richard Janko, another big name in Classics, based on more comparisons, argues that it's a version of an older, Ionian text that has affinities with what we find on gold lamellae (gold plates shaped like leaves, bearing messages "from" the dead and connected with Bacchic mysteries). The image of milk/milking (cf. the she-goat in the text summarized above) recurs in gold lamellae.
Obbink thinks this is an artefact testifying to a mystery religion. I forebear defining that term. Is Christianity such? Some likenesses and some differences ... It's not clear that these tablets are from a mystery religion, though, in the sense of a cult that is private and not public. Other scholars think they are protective incantations but perhaps used by public priests as well as private individuals.