A funeral club, so I am told, is where a collective: a society or group of friends agree to do a joint venture once they pass away and in order fulfill this wish they contribute to a fund.
I quite like this idea, you could be cast into public concrete sculpture or similar.
However I think a woodland would be better. I was reading about a group of strangers that bought a woodland near Stroud in Gloucestershire, UK. The collective have cleared the overgrowth, planted and nurtured the plot into something quite special.
So what about putting into a fund that bought woodland. And those coming after – well their contribution could be used for general husbandry, then you have: something in perpetuity; accessible yet private; natural which can be used to increase a range of wildlife and habitats.
Doesn’t need to be massive, keep your eyes peeled and you could have something lovely. What is more, if it is in your ownership I pretty sure you would not need planning permission, if you kept the scattering within those who own the plot…