HAHAWald Jager said:You can be buried in a cardboard casket if you want. Most cemeteries require a concrete outer vault mostly so you don't have a cave in when the casket desinigrates. Also in some places near rivers a vault is required to lessen the chance of upheaval and floating away. There are lots of places that will allow direct burial.
About the only law I'm aware of is you need 3' dirt above the burial. Worked in a church cemetery for 2 years in between maintenance jobs. Kind of a creepy job but you are your own boss out there ,not much feedback from the customers.