I am certainly no "expert", and am easily fooled by online images of coins, but if this were lamination or another form of planchet flaw, the effect would be incuse to the field..... these features appear to be in relief of the field, and therefore Post Mint Damage.
My imagination leans toward silver solder, as if this coin was used as an artist's pallet while a coin doctor was doing restorative work on another coin... I feel that the feature under the neck base is of the same nomenclature.