I would find it difficult to know someone is in the back garden, however much I loved them.
I find it hard to understand people perpetuating unexpected deaths, particularly road accidents. When I lived in Brighton, for years a family tied fresh flowers every day to a lamp-post on the road across the racecourse where their son was killed. Here, a schoolgirl was killed by a car in 2002 - her family have made a shrine with plastic flowers and a plaque stuck on a hoarding, and there was uproar when it was proposed to take down the hoarding and build on the site. I accept it's very hard (if not impossible) to come to terms with a death like that, but how do you ever have closure if you tend a memorial daily? We leave flowers on my parents' graves, but on special days, not all the time....