This wildflower has numerous irregular flowers (code 1--) arranged in dense clusters.
This is a wildflower with alternate leaves (code 13-) that are each divided into three parts (code 134). In the Locator Key, under Group #134, we find three choices: Leaflets 3..., Leaflets 4..., or Leaves deeply cleft...? Our plant has leaves with three leaflets. Are the flowers yellow? Nope. Is the middle leaflet stalk-less (or nearly so) or distinctly stalked? Looks nearly stalk-less to me. Okay, our plant should be on page 60.
The first listing on that page is Clovers (Trifolium), and the first line of the description matches our plant. Of the four choices within the group, only White Clover (T. repens) fits. Our plant is actually illustrated on a different page of the guide, as sometimes the plant appears to have only basal leaves (code 124). So in our case, at least two paths lead to White Clover.