It is and it is not. Apparently, there are a lot of different kinds of plants that are all falling under the morning glory category. The one we mostly know and is grown as a flower is not edible. Here is a wikipedia entry :)
https://en.wikipedia.org/wiki/Morning_glory
We always learn more!
Morning glory
Morning glory (also written as morning-glory) is the common name for over 1,000 species of flowering plants in the family Convolvulaceae, whose current taxonomy and systematics are in flux.