What in the world is that?
It seems that you can tell the health of your soil by the weeds that show up in your yard and garden.
Different plants thrive in different conditions. If you have an abundance of a particular weed, it should tell you a lot about your yard. Remember that weeds are not a problem but rather a symptom. Treat the problem and the weeds will often (but not always) go elsewhere.
Here are some examples:
Moss, Mullein, Wild Daisies: acidic soil lacking in nutrients
Chicory: rich soil, possibly alkaline and compacted
Plantain: compacted soil lacking in nutrients
Dandelion or burdock: compacted soil, lacking nutrients
Crabgrass: compacted soil that lacks calcium
Purslane: high phosphorus
Dock: wet soil
Fragile Fern: dry ground
Lamium: high nitrogen
Centaurea: high potassium
Wood Sorrel: high magnesium and low calcium
To be absolutely sure of your problem, send a soil sample to your local extension service or testing company.