If you are referring to Poison Hemlock, this biennial (2-year life cycle) plant is found across at least half of Maryland, including throughout your region (see map on the linked page). It was introduced to North America around two centuries ago, so while still considered to be invasive, it's not new to the area. Although it can be toxic if ingested (people and livestock), and sensitive individuals might get a skin reaction from sap contact (though there seems to be conflicting information about this risk), it's not too big of a challenge to remove if you can keep after it with the appropriate herbicide or (with personal protection) physical removal techniques. If you are interested in a presentation about this or invasive weeds in general, you could inquire with your county Master Gardener program to see if they have a speaker.

Miri