For purposes of 'commerce'.
[spoiler=The 'Oh god, take it away' list]
Public chests of these items are available in my base.
[spoiler=The 'nominal trade' list]
Pretty much any 'trade' is accepted to compensate my effort in collecting it.
Decorative stone (Andesite, Granite, Diorite)
Any food crop (or come by and harvest/replant yourself)
Cactus (or harvest/replant yourself)
[spoiler=The 'make me an offer' list]
Exchange rate depends on supply.
Feel free to put up your own 'surplus stashes' for bartering convenience!