What sort of resources are you interested in?

Japan had access to plentiful forest (though they deforested much of the islands, which in fact lead to a vigorous reforestation program and forest control policy); they had access to silver, some metals, and grew rice among other grains.

Keep in mind; that even during the period of Sakoku- the Japanese still allowed, the Ryukyus, the Chinese and in a more limited capacity, the Dutch to trade in Nagasaki and there was a certain amount of smuggling that took place between the Kingdom of the Ryukyus and Kyushu (or the more disaffected parts of Southern Japan)