Observe your yard before killing all the "weeds".
Wild Lettuce (Lactuca virosa ). The white milky sap secreted from the stem-cut is Lactucarium. It is known as lettuce opium because of its putative sedative and analgesic properties. The plant was used in the 19th century by physicians when opium could not be obtained (often referred to as the poor man’s opium). It was studied extensively by the Council of the Pharmaceutical Society of Great Britain in 1911. In the United States, the plant experienced a resurgence in popularity in the 1970s. Today the plant is un-scheduled by the Food and Drug Administration (FDA), meaning it is legal to grow, purchase, and own without prescription or license. Use young leaves for salads, extract sap for analgetic purposes, and dry all parts to make tea.