You may want to call them first then you aren't driving all around. I would start with tell them that you are looking for pallets that are no longer needed to build a coop, ask them if they have any pallets that they aren't needing anymore, and if they would be willing to let you pick them up...
And defiantly post pictures of the coop you make. I love the way the pallet coops look and that they are made from repurposed materials. You are going to have a blast making the coop!