It has to do with Improper Alloy Mix. Which can result in in what is commonly called a wood grained cent or Woody. And also Lamination errors. Your coin has a lamination error on the obverse with a mottled wood grain on the reverse. http://www.error-ref.com/lamination-loss-after-strike/ http://www.error-ref.com/improper-alloy-mix/
Thanks everyone, just wanted to double check and what I thought was PMD you pointed out was a lamination so good thing I asked.