My most recurring regret... building a raised bed system around my 'famous' front yard Dogwood tree.
Grew beautiful annuals...and KILLED MY MF'n 'Lady'.
The dogwood? Oh yeah... You never raise the soil level on a tree. Might have been alright if you built a well for it, but even at that, the roots are so far underground... I would have told you, had I been the installer... I am sorry. But, firewood
Might could be that if you tore it back out, she might come back in the spring... But prolly too late.