Make sure you know your options for retrieving your valuables if confiscated; that way, you can make an informed decision when confronted with a fast-moving situation.
By Mail
It may be advisable for you, if given the option, to mail certain personal property confiscated at the time they are taken into custody to a relative, friend, or attorney who can keep it in a safe place. Note, however, that you run the risk of being deported without those items, which will be especially problematic with respect to identification and money.
Pickup
If deported, CBP will not mail your leftover personal property anywhere. Leftover belongings can only be picked up by the owner or an individual with power of attorney.[1] It is wise to appoint a person with power of attorney in advance.
If you are unable to arrange for pickup of property, there are certain organizations that offer assistance in specific parts of the country. No More Deaths is one such organization.[2]
Petition
File a petition with Customs and Border Protection to get your possessions back. Recent changes require filing of the petition with CBP even if the confiscation took place through customs officials or through ICE officers.[3]
Theoretically, it should be possible to obtain the return of personal property and all or nearly all the funds seized by the government. It is crucial to a successful petition to show that the funds or assets were not used or obtained in the commission of a crime and that seizure of the funds would violate the excessive fines clause of the 8th Amendment to the U.S. Constitution.[4] Consult with an attorney regarding you petition.
[1] Available at: vice.com/en_us/article/what-happens-to-your-stuff-when-you-get-deported
[2] Available at: nomoredeaths.org/en
[3] Available at: ilw.com/articles/2010,0706-DuPont.shtm
[4] Available at: constitution.congress.gov/constitution/amendment-8