He apparently wrote a Planescape novel in '95, not adhering to whatever absurd history existed soon after he wrote it.
It wasn't picked up, and is published on the web here.
Fun quote:
Posted by Owlish at May 16, 2005 04:26 PM | TrackBack
You have to hold the berry lightly in your fingertips, testing the weight and texture in the fruit. Then you lift it to your nose and smell its bouquet-a light, sugary fragrance, with a teasing hint of musk. Then, and only then, do you slip it between your teeth and bite down gently... whereupon, you discover the sodding berry tastes like pure rock salt.