A weed is a plant that is not valued where it is growing and is usually of vigorous growth; especially : one that tends to overgrow or choke out more desirable plants. A plant may be described as a weed if found in one location and a wildflower if it is found growing in another area. There are however, certain plants that we would almost always consider weeds. Some may have food or medicinal value but we will not be addressing that here.

Spurge

Quackgrass

Below is a list of books that would be very helpful to identify your weeds.

Pigweed

Horseweed

Crabgrass

Buckhorn Plantain