It's likely to be State law, rather than Federal law, which is relevant in this case, so you'd need to find someone with specialist knowledge of the laws in the relevant state.
In the UK a police officer would normally provide a receipt for any item which has been seized but it's not automatic. The relevant legislation (the Police and Criminal Evidence Act 1984) only requires an officer must provide a record of what he's seized, within a resonable time period, if the person from whom it was seized (or the occupier of the property from where it was seized) makes a specific request for that record to be made available to him.
Most US Q&A sites are poorly moderated, and consequently full of trolls and spammers (e.g. Answerbag & Yahoo Answers) but you might find someone with knowledge of the state laws on Quora.