Need Advice for my little love.

I was supposed to be 9 weeks pregnant with my third child and my husbands first. I had an ultrasound when I started spotting and the doctor said I looked more like 6 weeks and there was no heartbeat and within a day and a half my hcg levels dropped dramatically and was having severe contractions. This morning I passed the amniotic sac on my pad. We don't know whether our baby was a boy or a girl so we named the baby Addison and well it just doesn't feel right to flush Addison down the toilet. I want to bury Addison in a planter with some flowers, that way if we ever move we can take Addison with us. Does anyone have any experience with this? Do I need to prepare Addison a certain way or the soil a certain way?