if you don't know what a pallet is than look at this
I only know of one place where you can pallets for free. That's at night in the back of Wal-Mart. If you are planning on going in the day time then you will have to pay for them. My mom works for a trucking company and pallets cost money so unless you want to steal them, your probably not gonna get them free.
I got mine at a lumber yard for free. Also, if you drive around behind business's you may find some. These things are all over the place if you know where to look. The merchants are glad to get rid of them and may even pay you to take them away. Lumber yards or building supply centers are your best bet.
If you're using pallets, you're probably shipping mdse. Try a local freight company. They usually have some laying around.
That might be difficult... Most companies resell the pallets so they dont give them away or throw them out....