Because we don't know what the pallets have been used for and we know we want to plant edibles in them, we decided to line them completely with thick plastic that we had left over from another project. (Hopefully, they'll last longer this way, too.) So, far we've built and lined one monster-sized bed: two feet high, two wide and twelve long. We've layered earth and partially composted leaves up about eight inches now. We plan on filling the planters at least halfway, then use our best compost mixed with top soil and other amendments for the top planting area.
After that, we'll build at least one more raised bed, and we still have to figure out the fencing--unless we're doing all this just to feed the deer. (At this rate, we won't be offering you too many tomatoes, cucumbers and peppers this year.)