First of all, what eco region are you in? NJ right? There’s lots of overlap between our flora and what’s up that way. Also, is the space you’re trying to convert full sun? Part shade? There’s something for everywhere, just gotta know the right tools for the right spot. What kind of lawn do you have fescue? To get rid of that I’d say spray with herbicide, a couple times, or solarize it with a nice sheet of heavy black plastic. Herbicide has a bad rap, and for good reason, misuse, but when compared so solarizing a spot it’s negligible. Herbicide, when using the right one, can be very effective and be less impactful on the area. Solarizing tends to kill everything under the plastic for a couple inches. This excludes all the great bugs and mycelium, etc. that’s so beneficial to the soil. Sometimes this can be beneficial if there’s an invasive that’s been dropping seeds. Solarizing will tend to sterilize the seed bank, so if unwanted seeds are there, it usually will kill em.
This is a reason you’d have to spray herbicide at least 2 times. Then the seed bank germinated, let it grow about 6 inches and then spray again.
After you have a nice clean slate, I’d say seed And plug with live plugs, from a locally sourced native plant nursery. Local ecotype seed will be well worth it for the success of the planting and speed of its establishment.
As for what to plant, we can discuss that more. There’s so many native plants in the US. We are currently working on a grant to reestablish perennial native food crops as an option for farmers to establish and bring to market, instead of doing the annuals and tilling every year. That’s another topic.
We converted the front 3 acres from lawn (Brome) to native 3 years ago, and the guy that sprayed did a horrible job. But we have been burning it every year and over seeding it and it is looking gorgeous now. It doesn’t take awhile for many natives to grow to large attractive plants. I could go on… Hahahha
Got too many flying around to keep everyones location in mind. I just remember your north east of me. 
but no one enforces it.
monsters.