Rhinestone, in my cousin's grave, in it, before it was filled in with dirt and worms. It was very dignified and impromptu afaik. They queued up, said a few words and dropped the things in, "enjoy it mate," "love you" "miss you forever". There were also flowers and petals and so on, but in truth, I think my cousin would have enjoyed the other things more.
It's an expression of loss and longing, for all the times you won't listen to that album together again, you won't have a pint and a fag together again but will always remember the times when you did. My cousin (and also my brother) were 'known' people. There were people who had never met my cousin but loved his music, loved his playing, loved the personality they saw (which was pretty much what he was like all the time) and who mourned the end of their dreams that they'd hear him play again, that they would never hear a new song of his, that they would never meet him at a gig and have a beer with him; those are dreams which people have lost, their lives are a little poorer for their loss, maybe there's a little less light, a little less to hold on to or look forward to.
Loss, love, grief, opportunity, hope. These are big things, and I would never judge people who try to express that by leaving gifts at a shrine. Better, imo, than the thoughtless and anodyne doggerel and gas station flowers, cards with pink teddy bears...... None of which had any place in Amy's life.