1. EcoSMART Weed & Grass Killer - $11 for 64oz: Touted as "The Safe Pesticide Brand," the active ingredients approved as Direct Food Additives or classified as GRAS (Generally Recognized As Safe) by the U.S. Food & Drug Administration. Though the label does direct you to keep the product out of the reach of children.
2. WorryFree Organic Weed & Grass Killer - $6.98 for 12oz: Uses d-limonene, the citrus oil that is extracted from the rind of oranges is a concentrate that will make over a gallon of weed killer. It is listed by the Organic Materials Review Institute (OMRI).
3. St. Gabriel Organics Burnout II - $19.95 for 64oz: Made of food grade ingredients, it is labeled as an all-natural, non-toxic, food grade organic weed killer. It has a 100% satisfaction guarantee.
4. Perfectly Natural 100% Organic Weed, Grass & Moss Killer - $29.99 for 64oz: It says that it will show results typically within an hour and a single application will kill most annual weeds (while perennials may require a follow-up application). Made without synthetic ingredients it's said to be safe around kids and pets.
(Images: as linked above)