The only place where i found the leaving of physical objects to have a resonance and relavence, was the Viet Nam Memorial in Washington.
If an vets' deaths are attributed to war injuries, their names are still added, so there are half-a-dozen new names added every year.
All the 'physical' memories are collected by volunteer attendents at the end of each day, and stored.
There are plans for a memorial museum to be built, but it has to come from public subscription - the government does not fund memorials.
One guide told me of some of the things left - a wedding dress by a bride whose dad was not there to walk her down th aisle, a $10 bill left - an unpaid debt before the lender was drafted - it's all heartbreaking.
The biggest item so far is a brand new Harley Davidson motorcycle, which still has the dealer tags attached. It was left by the wall one day, and the volunteers tracked down the people who had left it. It was a local biker gang who had saved up and bought the bike to leave - 'In case any of the brothers need a ride ...'
Now that is a memorial worth having - very different from the way people here do it, because only people connected leave things, there is no mass 'mourn-in' from needy strangers.