Thanks for the question.

I believe this is Ground Elder (Aegopodium podagraria). Its common name is Bishop’s goutweed. It is not fun to have around! It spreads via structures called rhizomes. These originate from the stem of the plant and grow horizontally slightly under the soil surface. They are the white, stringy things seen in your picture. It is a plant that is extremely hard to eliminate. Even small pieces of the rhizome can produce a new plant. It is a perennial and keeps coming back to visit you year after year after year. It has white flowers that produce a very large number of seeds.

Remedial steps are:

1). Remove the flowers when they first appear before they go to seed. This is easier said than done since the flowers are extremely small.

2). As you discovered, broad leaf herbicides containing 2,4-D, dicamba, MCPP, or combinations have minimal impact upon goutweed. While these herbicides may cause browning in the leaves, they are not reliable for eradication of the established rhizome system that characterizes goutweed.

3). The herbicide that is usually employed for the eradication of goutweed is one containing glyphosate. This is a nonselective herbicide, which means it kills all plants that it contacts.

4). If you use glyphosate to eliminate the two goutweed patches in your yard, be prepared to reseed those areas this fall after the goutweed is gone.

5). There are two effective times at which to apply glyphosate. The first, and soon coming up, is late May through June. This would be prior to flowering. This is the easiest way by which to prevent seed production. The second window is late August through September, while the foliage is still green and healthy. 

6)..  Avoid tilling the areas containing goutweed.  This will only fragment the rhizomes, facilitating the spread of the plant.  Avoid pulling it up from the ground.  This will achieve nothing as the rhizome system typically remains in the soil.

See the following for further information on these and related points.

https://www.minnesotawildflowers.info/flower/goutweed

https://plants.ces.ncsu.edu/plants/aegopodium-podagraria/

https://www.maine.gov/dacf/mnap/features/invasive_plants/aegopodium.html

https://www.ontarioinvasiveplants.ca/wp-content/uploads/2022/05/OIPC_BMP_Goutweed_April122022_D3_WEB.pdf

Good luck with your upcoming venture. Please get back to us with any related questions. Thanks for consulting us.