http://bcfarmsandfood.com/weeds-that-indicate-soil-conditions/

Nice to have a different method to assist in verification of soil type.  Our home is built on a former corn field.  No way to know what chemicals and soil amendment methods the farmer used on this land, but I am grateful.  Our lawn soil tends toward being a bit on the clay side, but pH neutral and quite fertile.  I've never seen a patch of land with more worms.  I can count the number of harmful grubs I've seen, converting a quarter of our yard to garden, on one hand.  I've home tested different parts of the lawn.  Next year I may get it professionally tested, but then again, my garden successes and challenges have already provided and confirmed some key details of our local soil composition.  So far, bindweed absolutely loves my yard.