80 Reis of Maria I

This 80 Reis coin was struck in Brazil, at the Rio de Janeiro mint, while the Portuguese court huddled in exile from Napoleon's armies.

That makes it a rare example of colonial currency produced far from the mother country, using whatever copper was on hand. The obverse shows Maria I's profile, encircled by the date and denomination; the reverse bears a simple coat of arms, all in a style that screams wartime efficiency. Mintage figures? Those went up in smoke during the 1838 fire at the Lisbon archives, so we're left guessing.

One oddity: the coin's edge is sometimes reeded, a pointless flourish on copper that might have baffled the minters. As for myths about hidden treasures, I've heard enough—it's just a workaday piece from a turbulent era.