I never really understood the need to be buried in a coffin after you pass on. Just cremate me and throw my ashes on the ground to fertilize the plants. Enough of these grave real estates
this is why i think we should turn cemeteries into parks, where you just choose a place for a little sign which will effectively be your grave, just that you become nutrients for the surrounding plants.
I read that the ash is actually quite bad for fertilising plants... And it might even hinder the plants growth... I don't have the source handy, unfortunately...
So if you want to be environmental, your best bet is probably to be composted (only legal en very few places) or buried in a cardboard coffin.
Arranging to having yiur future postmortem body used to fertilise plants, is a really cool option, in my opinion. A green/natural/eco funeral is one way to, basically, do that, and it's pretty widely avalable too, in most places.
And cardboard coffins work, and tend to be accepted by mat green burial sites. Woven willow coffins, untreated wood coffins, as well as just classic biodegradable shrouds, are several other options that used for this.
On that subject,Hheres some resources that might be helpful with planning for a green burial, ahead of time (and ensuring that thise wishes are carried out later) , for those that this appeals to and that haven't allready: https://www.orderofthegooddeath.com/resources/green-burial/ (the order also has information on n. o. r/terramation/composting, and on aquamatuon/water-cremation options, both of wchich are compatible with the 'become plant ferileser if yiu wnat to' idea) and https://www.greenburialcouncil.org/interactive-maps.html