We go through pallets at work all the time. A lot of people shy away from upcycling pallets because they think they will bring dangerous chemicals to their environment. But it is actually really easy to find a good, clean, safe pallet by looking out for a couple of quick things. I look for two major things: the seal showing the initials HT and a pallet that looks like it has only seen use one time.
For full information about pallets and how they are prepared, how to choose one or where you can buy a brand new pallet - here is a great article