What a sad turn of events, so sorry. Huge hugs to you...
We have a spot by our raspberry patch with a burial plot for a chick we lost during its' first week. My boys even mark it with feathers from the flock members or flowers. It is close to our coop, so she can "be near" her sisters (and temporary brothers). I like knowing it's there for some reason.
Our BR, Dumpling, who died in March is also buried in our yard. I like knowing that she's in the yard with her "sisters". I still miss that silly girl.
I am soo sorry for your chickie. That is so sad, but now she is not in pain and suffering anymore. You did the right thing by taking her to the emergency vet.
She will be there forever watching over you in the garden.