By late summer, Common Dandelion (Taraxacum officinale) can lie under the radar. Having flowered and fruited en masse in the early part of spring, most plants you'll find in August will be all leaves. I've recently located plants with lush basal rosettes growing on the edges of cultivated fields.
Practiced foragers generally recommend that those new to consuming dandelion greens aim for the early, young leaves that are available prior to the plants flowering in spring -- as they tend to be less strongly bitter. But so long as I mix the leaves with milder components, I find the strong flavor of even late summer leaves to be a welcome treat. Dandelion greens have extremely high levels of vitamins and minerals, and in the right places they are large and abundant. Plus, they look delicious!