First I want to say, I am sorry for your loss. My beloved Kent, 11 years old or so also passed away recently, 7/17/16. I got him at the local shelter and the guess was he was 2 or 3 at that time. I wanted to plant flowers on his resting place, as well. I am not certain what I will plant, but a dogwood tree might be nice, as they do well shaded by other trees and you can start with a small one. They are beautiful in spring. God bless you and your family. You can see my Kent on YouTube if you look up Kent loves buns. He loved bread. Also smiling dog may take you to the video. I miss him so much.