“Ownerless” (hefkeir) fruit does not require having teruma and ma'aser separated even after it has been brought into your house.

Halachically ownerless (hefkeir) fruit is fruit that will not be collected or picked by or for the owner, whether the fruit is:

• Still on the tree or fallen on the ground.
• Growing on public grounds or privately owned property.

 

For shilu'ach ha'kein, the bird, eggs, and nest must be wild or declared ownerless (hefkeir) with three adult, Jewish, male witnesses.
 

If you inadvertantly buy chametz on Passover, you must burn it.
If chametz was brought to you, such as by mail delivery service, DON'T accept it. Consider it as ownerless/hefker. You may not bring it into your house or yard. If it is still there after Passover has ended, you may take it for yourself.
Note If  you inadvertantly bought kitniyot during Passover, just put it away until Passover has ended and then you may eat it.