Nobody seems to have mentioned straw bales.
My preference would be for railway sleepers but I have seen straw bales used
with some success.
Cheap(ish, depending where you are), green, effective, just not very
permanent.
Good luck. I'll be looking at this myself soon.

B

"Tony" tmg124AThotmailDOTcom wrote in message
...
Hello all
My wench wants me to build a vegie garden this weekend, but she is
concerned
that treated timber will contain poisonous chemicals. I need to raise the
vegie beds, so any suggestions on what to use.
Thank you.