place a add on Craig's list asking for them. if you have a truck some people will say if you can come and remove the pallets from my property then they are free. a lot of the big stores like Sam's and wall mark get their merchandise on pallets so you can call the stores and see where the pallets go from there. ask them if they are will to set some a side for you.
Check out Freecycle in your area. You would be amazed at what you can get free from others who don't want things anymore. (BTW...great place to give your things away that you don't need anymore but someone might want.) Here's a list of all the Freecycle groups in Michigan. Just click on the closest one to you.
Also, go talk to the manager at Lowes or Home Depot...flooring stores, plumbing supply stores, electrical, hardware, etc. Many are glad to get rid of the pallets. Many stores have to pay to have them removed so they are only too glad to give them away.