Cheers Jim! And yes I do for the above mentioned tea-stealing scenario! 
Any idea what a tea chest looks like? 
James
Just normal boxes really, possibly with the producers mark on them. The first tea exported from Japan was in 1610 by the Dutch.
The Perry civilian carrying the two loads on a shoulder yoke could be carrying tea.
I'm not 100% sure whether the boxes were tin lined or not as early as the Sengoku period, I'm getting my wife to look into it. They were certainly tin lined in the Edo period as Japan's export to the international market increased dramatically.
Tea was considered more of a rich mans pursuit so an ambush to steal some from I rival daimyo would make for an entertaining little skirmish
cheers
James