I did get a Stonemason’s Guild Band a couple weeks ago, out of a 370 Ring and Trinket box (Tortollan Trader’s Stock) from a Tortollan Emissary quest iirc.
Didn’t get any other “non-regular” (i.e. ring/trinket oder weapon) caches yet, but I guess that’s only a matter of time. Will keep you updated if that happens. 