Grass ID is challenging and relies on fine structural details to separate similar species, and these can be hard to photograph well for an easy ID (and they are sometimes even hard to see well in person without magnification). Examples of these physical features include ligules, auricles, collars, vernation, flower or seed head structure, and growth habit. We'll share two links below as examples of what these structures look like and where to find them. Although the pages below are used for the ID of turfgrasses, the structure types are the same across all types of grasses.

• Turfgrass Identification Key - Ohio State
• Cool-season Turfgrass Identification - Penn State

Our initial impression of the grass in your photos is Broomsedge (Andropogon), in which case it would be native. Several Andropogon species occur in Maryland, and the type of habitat you're finding it colonizing sounds right for their preferences.

Miri

Unfortunately we can't determine its ID without more information, and details we either can't see clearly in the photos (some are not in focus) or seem to be missing entirely from the pictured plant sample due to mowing. If you can, let one or two clumps flower and start going to seed so we can compare those attributes since seed heads are a very important identifying feature. (Since you have so many clumps of this grass already, having one or two produce a few seeds before it's cut again won't matter much, even if it is a weed.) We don't have a key to all the grasses that can grow in MD (they number in the several hundred) so it will be difficult to sort out which native grass this is (if this is not a non-native weed). Certainty about the vernation is key to making any progress with grass ID keys, as it's the first point of selection to move down the list of other traits.

For what it's worth, Andropogon has folded vernation, a membranous ligule (though there are many long leaf hairs right next to the ligule, which can confuse things without magnification), and no stolons or rhizomes (bunching habit only). The flat-compressed nature of the leaf clusters is a trait of Broomsedge. Other traits can be found on these pages:

• Broomsedge - NC State Extension
  * Note that this page deals only with one species of Andropogon, and while they consider it a turf weed, it is a native grass that can be a valuable plant for more naturalized areas like meadows and sunny clearings that are not turf
• Guide to the Identification of Grasses - turf industry publication hosted by Michigan State University's online library of reference material
  * This comes closer to an all-encompassing key, even though it covers some grasses that don't occur here in the mid-Atlantic. Broomsedge data is on page 56 of the document, under grass species number 32.

Miri