I completed the 2x RU of the lawn, ordered the seeds and once they arrive I'll be ready to go. One problem, our home builder needs to do some work in our house that will require a cement truck to drive over the backyard. It will be a couple of weeks before they start, but I won't afford to wait. I plan on seeding everything and then hope for minumal damage. They said they'll lay sod down to fix any damage that they do. That seems like my only option, unless I wait for another year.

I say stiltgrass too, from sad familiarity with the little buggers. I have it in my gardens, not my lawn, so herbicide use is out for me. Here's a page from one of the invasive plant websites, with some recommendations for control. Good luck! Here is a link that might be useful: Stiltgrass

OK! Right plant, wrong species! That's why I asked where you were located. Maianthemum dilatatum is exclusive to the west coast. Wasn't aware there was an eastern version :-) And this is a wildflower - not necessarily a garden escapee. The tarp could help but it will also smother the grass. And it is not that effective for plants that spread rhizomatously (via underground stems). The rhizomes just keep growing to where the tarp doesn't cover and then pop up. Depending on how shady the area is, you might just want to encourage it and skip the lawn. Lawn grasses are difficult to encourage to lush growth in very shady locations and a shade loving groundcover - like this - is often recommended as a suitable replacement. Otherwise, containment would involve some sort of root barrier/edging at the edge of the lawn and some targeting herbicide applications. Any broadleaf weed killer for lawns should work well - the stuff can't tell between a 'weed' or any other type of broadleaved plant. Just spray individual leaves directly and be sure none gets on anything more valuable.

Yes, that looks like it and would make a lot of sense, so it's almost definitely that. From what I understand this should be ok considering what the owner wants. I've already offered to enhance the turf, and even though I'm paid well, he simply doesn't want to at this point. Japanese Stilt Grass sounds like it should be able to handle mowing