1940 & 1941 Lincoln Wheat Cent Wood Grain, Lam Error Also?

Both coins are woodies.
If you look at my 1956 cent in the pic I'm providing you will see waves of metal running perpendicular to the length of the lam. These waves are characteristic of a planchet because of how the metal is rolled to thickness. The reverse of the OP's 1940 coin has these perpendicular lines showing darker than the directional flow lines so that it gives the illusion of a different flow direction.

Have you watched anyone making home made noodles? When rolling out the dough, if there is a loose piece on the batch and it gets rolled into the lump, then it is there, but is not attached firmly or part of the lump. The same with copper. When the metal is rolled flat, if there was a part that was rolled onto the metal, it attaches, but is not part of the mix of metal. When these are cut in blanks and the proto rim

is added to the blanks and becomes a planchet, then that setup process can loosen the attached metal, because if was not in the mix. Then this will peel off the planchet before/after the strike. Thus like the example above, it peels away as it was not part of the mix, but rolled onto the stock material. Thus referred to as a lamination error.

These tend to run in straight lines as the shape of the metal if rolled into the new position, making it longer and thinner when it attaches to the original mix.


Sometimes it is a piece of debris that get struck onto the coin.
Rim bur:


Debris: