After having the GMs check one I couldn't find for a long time (and no one else could either), I knocked out two in one day.

>In the driftwood crate you see a large blue iolite, a small yellow-green alexandrite, a medium clear aquamarine, some platinum coins and a cambrinth armband.
>You get a polished bronze armband inlaid with cambrinth horned owls from inside your driftwood crate.

>In the brass strongbox you see a small mint green emerald, a huge swirled rust-colored quartz, a tiny faceted pink sapphire, some platinum coins and a glaes belt knife.
>Perfectly balanced, the blade was likely the subject of many hours of labor, given the detail of the design. While retaining the metal's lustrous blue-black hue, the curved glaes blade has been expertly honed to a fine edge and etched with a repeating spiral motif.

Working on the third one now. Thanks all who helped, and the GMs. And if anyone's interested in the armband or the knife let me know.