Consumer Protection Law
Consumer Protection Law Questions? Ask a Lawyer Now.
Without more details about the search, it's not possible to say whether the police violated your rights under the 4th Amendment to the Constitution. But it is safe to sayin general that once they have stopped you the police can seize any contraband in plain view. If you consented to the search they can search your vehicle. If you didn't but you were arrested, they can make an inventory search of your vehicle incident to that arrest.
If the police remove any of your property as evidence or for safekeeping, there would an inventory or vouchers of some kind for that property. Whether it's the policy of the towing company to itemize what's found in a vehicle they toe and keep such a record would vary with the particular towing company.
Unfortunately, in situations like this, what in my experience will happen is that the police and the towing company will not have any paperwork which will show that there was cash in the vehicle and that they will claim claim "Money? What money?" when you ask about your funds. Yes, then you can sue them, but whether you can meet your burden and show that there was actually money in the car will be another story, so don't try to do this yourself without a lawyer if the police and tow company claim not to know what you're talking about.