The weeds pictured don't look like Dichondra, but do appear to be common wild violets (potentially Viola sororia, since it's very widespread among the 30-ish violet species native to Maryland). They are native and beneficial for pollinators, and serve as a caterpillar host plant for Variegated Fritillary butterflies. Given those benefits, some gardeners opt to allow them in lawns.

If too bothersome and you want to remove them, your only options may be to physically dig them out (filling-in the bare areas with sod, or seed if you can wait to do that in late summer or early autumn) or to use an organic herbicide. Montgomery County lawn pesticide restrictions likely prohibit the use of a systemic root-killing product like glyphosate, though this will depend on whether you live in the except municipality or not. Organic herbicides will only kill the foliage, so repeated applications would be needed to gradually weaken the plant by forcing regrowth that uses-up root energy stores. Even so, such sprays tend to be non-selective enough that they might also injure any turfgrass contacted by the spray.

Miri