Nope, not a Corn, and definitely not a Copperhead. This is an Eastern Milk Snake(Lampropeltis triangulum triangulum), a member of the family that includes the King Snakes. The pattern on the head is different from a Corn, and these look nothing at all like a Copperhead, not even close.

Sharp-tailed Snake (Contia tenuis). Harmless slug eaters.

Appears to be an anerythristic corn snake. Quite common...who ever had the snake should know that and have further information for you.

The only poisonous snakes in Wisconsin will have a rattle at the end of their tails. Also, those are very very rare here. Also, snakes are your friends. They will keep rodent populations under control. They are generally very shy and won't bother you unless messed with, or stepped on (do not try to pick up).