Check your local laws, because some areas require ANY vehicle sitting in your lawn to have tags.. regardless of its condition.
In some areas a bill of sale alone will not legally establish ownership of a motor vehicle, it just establishes that you didn't steal it.
Most laws don't distinguish between a freebee junker and a $180,000 sports car.. in neither case does the "I dunno man, some guy just gave it to me" or "It was sitting in the garage when I bought the place" excuse enough to get you out of a reieving stolen property charge.
Most junkyards are required to keep some kind of paperwork on every vehicle on their lot.. known as "salvage" titles.. you may wanna check with your local DMV/Highway Patrol/City official to find out what your requirements are by law.. but at the very least you should have a bill of sale with the name and address of the person you got the vehicle from.
In some states its flat out illegal to posess a motor vehicle that does not have a VIN or serial number.. but none of these senerios really come into play unless you've got John Q. Law nosing around your place.. and that normally dosen't happen unless you've had a neighbor complain about your private junk yard.
