1940-S Mercury (Tossed In Another Photo With Highlights)

Looks like you may have a coin that has been from a die clash incident. You've seen the scratches on a coin from die cleanings? This is because of such an incident as a die clash. The two dies strike together because there is no planchet between them. When this happens you can see the outline of the field next to a device. It is an outline because the dies out side edges touch each other. The outside outsides of the die is the fields. The devices (Letters/numbers/designs of bust and reverse is deeper into the die. so when the dies clash together, they only show the outlines of the obverse and reverse on the opposite dies making the marks that you see on your coin. Here is an image of the position of the two dies and note they are flipped horizontal and 180 rotated as that is the position they would be in while striking a coin. The images can show where to look for a die clash. Remember just the outline in the fields will show and often not all of the die, but usually just parts show.

Hope this helps. If not ask another question.