My lovely Trouble, who I had had from birth due to a miscalculation on my part, was PTS just before Christmas coming up 4 years ago is buried in the garden with a lovely white Rosa Rugosa Alba on top of him. I still miss him like crazy, but it DOES get better with time. It is a comfort seeing his rose. He was 18.
I would suggest not throwing his things away, sooner or later, possibly sooner given the age of Robyn, you may consider another cat. It will never replace Leo, but although some cats are very special to us, your heart expands to love another.
Thinking of you both.