Saw a beautiful cemetery while on vacation.

https://theherbladyblog.wordpress.com/2017/09/05/wild-thyme-in-the-adirondacks/

I do not know where you are, and the conditions of the graveyard. Here in Texas , some one found Salvia farenacea "Augusta Duelberg" and "Henry Duelberg" growing at Augusta and Henry's grave. They had been growing there for years untended. They are now sold on the trade bearing the names of the graves that they were found at. I would look to plants found in old gravesite. Some of these are now sold on the trade. They are good at withstanding the tests of time. A white iris that was originally a plant that moroccans used in cemeteries in Morocco was brought over by slaves is another one that one finds down here.Iris are tough plants on the whole and last a long time. I have some of these white irises. They are bullet proof. I think there are some sites that have gonbne and done their plant collecting from ole cemeteries.

You got me googling "Plant Collecting from Gravesites" because I was trying to find some nurseries that had gotten some of their material from them. I found this article about People in Philly restoring "Victorian Cradle Graves"

Ritual plants used in Graveyards around the world

There is a list of many gravesite and their regulations and intent, i.e. Natives to help with wildlife and stuff like that. LThere is a lot of good reading on the web. I definitely would check with your cemetery and see what their regulations are. I would walk through some old neighboring cemeteries and look at what plants are doing well with the minimal care in your area.

In our cemeteries, plantings are futile, because the caretakers will weedwhack and/or mow it to death. I like seeing ones where plantings are possible.

Sometimes there just isn't enough time to get everything done, so it's a good idea to make an area so you don't have to clean on it.

Hey there, sorry to hear about your losses. It's great that you're thinking ahead and making prearrangements for yourself.