Just put it in a bag, extra water is not necessary. Tape the bag up real good so it doesn't leak. Use some newspaper to help insulate the moss a little and also soak up any potential leakage. Throw it in a small poly mailer bag, weigh it, and use paypal click and ship to send it. Another alternative is to use small flat rate boxes from the post office. It costs a little more but you don't have to worry about weighing the package.
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