I seems that people find them out back at places like Lowes Walmart, etc. See here: http://www.hometalk.com/416830/where-do-you-find-free-palled-sp-boards-love-the-idea
Hey Jessica, when I built a compost bin out of pallets I got them from my tile vendor. For my project, this worked out great as they were untreated pallets. Good luck!
thank you so much, I can't wait to make something and post it.
Jessica, can't wait to see what you do!