If you received something in the mail that you did not order you are not obligated to return it in the state of Louisiana. Can someone verify this?

Im pretty sure someone can verify it for you just look up the senders address and or company
If the package you received is not addressed to you, then opening it or refusing to hand it in is actually a violation of Federal law in the US, which applies to all states.
You must make an effort to either return it or hand it into a postal office. Opening it is a criminal offence. Refusing to hand it back over is theft.

If the package is addressed to you but contains the wrong item, you are recommended to hand it back over for a swap. It may be company policy that they will not correct the order until the wrong one has been returned, and usually these polices have a time limit (mostly 2 weeks) to return the item for an exchange. In this case:
  • It MIGHT be a theft if you refuse to hand over the wrong item, because that could be someone else's order. But some large companies may let this slide on occasions if the value of the product isn't worth them arguing over.
  • It WILL be seen as theft if the wrong item is considerably worth more than the item you ordered (for example, if you ordered a $20 bracelet but end up with a $800 TV and refuse to hand it back, that will definitely be a theft).

In both cases, you should not have to pay fees to send the items back and the majority of good companies will not charge you return fees. However those smaller companies that do so can be contested.