Treasure! Literally! A hoard of Roman gold and silver, including jewelry, figurines, and a lot of these votive “leaf” plaques.
A votive plaque like these was part of a religious offering, a small, thin wafer of gold or silver. From the description of item #8 on Wikimedia Commons:
9) Slender gold votive plaque, now detached from its uppermost position on the stack of six gold plaques. Embossed in the centre is a schematically-rendered slender gabled shrine, with a volute-ornament at the apex of the gable. In the shrine stands Minerva, lightly turned to her left, holding a spear in her right hand and a shield in the left, and wearing a crested helmet. Above the shrine is a simple leaf-marked finial. Beneath is a punctim inscription in a tiny ansate panel. The basal tab has been squashed back against itself. Together with a little damage, this has obscured part of the inscription, which appears to read
CARIAT IA REST VSL M
indicating that a person named Cariatus (or Cariatia, or similar) dedicated the plaque in fulfilment of a vow.
Height 135.3 mm. Weight 5.7 g.
Though they’re not sure why it was buried, it seems likely that the whole hoard consisted of offerings to a shrine of Minerva… although some of the items are engraved to a goddess named Sena or Senuna.