Dandelions are also edible...
And if purpose cultivated in a garden they would be OK. But this is a chitty city too big for its breeches.
I think dandelions and lettuce are loosely related - in fact there are a large number of plants, like dandelions, that are edible.
A plant that has a latex base (milky colored sap) and has yellow flowers that form clocks has a good chance to be dandelion-lettuce related.
Here in the Seattle area, I could easily point out four or five variations of wild lettuce. Most (just like store bought lettuce) will get more bitter and tough as they reach the flowering seed-bearing stage.
But all are cool-weather crops, that bear alot of seed, and are easily germinated.
Good SHTF knowledge.