In some places you can go for a 'natural' burial where you are minimally processed and simply placed in the ground in basically a natural material burial shroud.
In a lot of places, however, this is highly illegal and there are minimum requirements for burial (which can include embalming and/or a casket and/or a concrete and/or a burial vault which is basically a concrete sarcophagus that caskets go in).
Here in Indiana the only requirement is you have to be placed in a designated cemetery or graveyard 'within a reasonable time' however, pretty much every cemetery here requires a casket and a burial vault.
I used to bury people for a living and always found it so dumb, I'd have to excavate the grave, get chains under a vault and lift it with the backhoe, very slowly drive it out to the grave to prevent it swinging and cracking, lower it into the hole, go put the backhoe up, come back and jump down int he grave with a dust pan and get any dirt that fell into the vault and climb back out without knocking more in, cover it with a tarp and a piece of plywood then do prep an hour or so before the body was to arrive to have it ready for the graveside service.
Then... people would throw handfuls of dirt into the vault eyetwitch and after they left I'd remove all the fake grass and stuff, go get the small tractor, wrestle the vault lid into the front loader bucket, slowly drive out to the grave, wrestle it out of the bucket and get some straps on it, lift hte straps with the bucket and lower it down, let slack out slowly on one end to lower one side of the lid on, remove the straps, lower it more and then play 'don't crush my fingers' while I'm laying next to the grave trying to get the straps out without slamming the lid down and breaking it.
THEN I could put the dirt back and get back to cutting several acres of grass and walking around with a backpack full of diesel to weed eat while trying not to get sun poisoning again.
Laws requiring embalming/caskets are pretty uncommon. There aren't any laws at the US Federal level, and only a handful of states have any restrictions. Finding a funeral director to provide a natural burial can be more difficult, although most large cities have at least one option.
In a lot of places, however, this is highly illegal and there are minimum requirements for burial (which can include embalming and/or a casket and/or a concrete and/or a burial vault which is basically a concrete sarcophagus that caskets go in).
Here in Indiana the only requirement is you have to be placed in a designated cemetery or graveyard 'within a reasonable time' however, pretty much every cemetery here requires a casket and a burial vault.
I used to bury people for a living and always found it so dumb, I'd have to excavate the grave, get chains under a vault and lift it with the backhoe, very slowly drive it out to the grave to prevent it swinging and cracking, lower it into the hole, go put the backhoe up, come back and jump down int he grave with a dust pan and get any dirt that fell into the vault and climb back out without knocking more in, cover it with a tarp and a piece of plywood then do prep an hour or so before the body was to arrive to have it ready for the graveside service.
Then... people would throw handfuls of dirt into the vault eyetwitch and after they left I'd remove all the fake grass and stuff, go get the small tractor, wrestle the vault lid into the front loader bucket, slowly drive out to the grave, wrestle it out of the bucket and get some straps on it, lift hte straps with the bucket and lower it down, let slack out slowly on one end to lower one side of the lid on, remove the straps, lower it more and then play 'don't crush my fingers' while I'm laying next to the grave trying to get the straps out without slamming the lid down and breaking it.
THEN I could put the dirt back and get back to cutting several acres of grass and walking around with a backpack full of diesel to weed eat while trying not to get sun poisoning again.
Man, do not miss that job.