Pennies with unusual metal Grain

Hello, I was going through a bunch of pennies and noticed that out of 20-30 different coins and year variations, a 1996D, 1995D and 2004D all have a very distinct grain, not like the normal look i see on the rest. any opinion is nice. Thanks

 

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Without a picture this is just a guess but it is probably woodies, planchettes were made with improperly blended metal mix that causes a wood grain like pattern on many cents
there are several thread on the forum about them

 

Here are a few pics, they were quite difficult to get, hope they'll be ok to judge by. Thanks