As a spouse to someone arrested on RICO charges, do I have any rights to get back any items seized if I was not charged in the crime?

At this point those items are more than likely considered forfeited evidence in the current RICO case against your spouse, which means that the property will be in the hands of the government until your spouse's case is resolved/adjudicated. At this point, assuming those items have not been sold off by the government in a asset forfeiture sale, you can petition the government for a return of those items to you.