One of the most common weeds in North Texas are various forms of wild lettuce. We have had entire salads picked from weeds in the yard. Less common and less aggressive than wild lettuce are dandelions which taste so much better.
An interesting note is that I have seen wild lettuce grow almost everywhere including both Afghanistan and the deserts of central California. Wild lettuce is called Lactuca from Latin which is where the English word lactose comes from. Lettuce gives off a thick white latex sap when broken which is a mild relative of heroine.