Recently, I've been serving a lot of foraged salads and most of them include Purple Dead Nettle (Lamium purpureum) mainly because I have a lot of it in my yard and flower beds. Purple Dead Nettle—not a true nettle at all—looks superficially similar to both the closely related Henbit (Lamium amplexicaule) and the unrelated Ground Ivy (Glechoma hederacea).
I prefer the very young leaves of Purple Dead Nettle (they're less hairy than the more mature leaves). You have to dress this plant very lightly in salads because the hairs collect dressing and it is easy to overdress a salad. I also use the younger bloom spikes, pinching them off the stems. The large square stems I discard. Purple Dead Nettle has an agreeable green flavor, with a smell that is slightly medicinal. Because it can dominate a salad, I tend to use no more than about 20% of Purple Dead Nettle in my mix.
In this photo, you see two stalks of Purple Dead Nettle rising above a field of Ground Ivy with the occasional violet (Viola spp.). Violets are quite edible, both bloom and young leaves. Violet flowers, like their domestic cousins the Pansy, have a slight floral flavor. I use them mainly for color in salads. The leaves are a bit earthy in the good way that Swiss Chard and the other beet greens are earthy. Ground Ivy (aka Creeping Charlie) is also edible, but I find it really medicinal, so I use it sparingly and mainly for the blooms.