Try low-growing wildflowers for the north east.

There are three plants I can think of off the top of my head that might work for you. One is Dianthus, it winter sows and spring sows really well, and there are lots of different kinds (not barbatus, that's Sweet William and is a biennial). My fave Dianthus is Arctic Fire. Has little red and white flowers.

The second is Saponaria ocymoides, it also winter sows well, and makes a nice ground cover. Little pink flowers.

The third is perennial Iberis (candytuft). The flowers are white.

You can google them all for more information.

I did one bank of wildflowers so I didn't have to mow or weedwack. Worked well for 2 seasons, this past season, the 3rd season crown vetch took over, I believe the birds went after the flower seeds and dropped crown vetch seeds, as I had the area cleared prior. This early spring I am going to have to clear out the bank of what I want to save and start over to get rid of the crown vetch.

I find Campanulas, Perennial Primula and Creeping Thyme work very well for smothering out weeds in my PA climate.
Both fill in fast and dense, invasive actually, unless you do have alot of room.

I have creeping sedum here that forms a very dense carpet. It's not a fast spreader from what I've seen the past 5 years. It hasn't appeared to spread more than a few inches in all that time. I didn't plant it--my brother did 15-20 years ago which is another reason I don't think it spreads fast or else it would have taken over a much larger area by now. It has little yellow flowers. It would take hundreds of seedlings to get the effect you're looking for. The iberis/candytuft is a good suggestion. I'm WSing that myself this year but can't say how it does since this is my first year to WS.
Vinca is a good ground cover but it won't choke out weeds--the steep hill behind my garage is a thick carpet of vinca but the weeds and briars come right up through it. I can't get to them because it's so steep.
There are lots of different ajugas on the market and that does spread fast. Have a look at arabis too. There are low growing euonymus but I can't say if those could be WS. There are a few different cultivars of lamium that have either pink or white flowers.

I think annual and perennial alyssums are amazing for coverage. Even if you decide to WS something else, consider buying a few cheap packets of these annuals and sprinkling the seeds around the areas in between plants to cut down on weeds. They bloom and bloom and then reseed for the next year. I've got the white "carpet of snow" (anual) reseeding around and between 3 large lavender plants in one area and they really help keep the weeds down.

I didn't intend it, but alyssum makes an excellent groundcover. Also you might look up the perennial kind of plumbago. Finally, you might google celandine poppy, go to the second link, go thru the pics where they have spread under a tree by self seeding. But you would have to order those from Prairie Moon.

Purple smoke from there some of us went gaga over should self seed and possibly become invasive, shorter plant but doesn't hug the ground.

Taller plants several might work, but I hesitate to recommend any. One I would but remember what it did for me. Smothered out weeds great the second year but had blotches of some sort on the blooms.

Iresine is an annual but would make a pretty ground cover and spreads maybe by runners but lays flat and roots along the shoots as well. It roots very easily in water so you could keep it going from year to year but have to keep it inside in the winter, might be hardy in your zone, doesn't like hot afternoon sun and doesn't like to get dry. It trails beautifully, too, one of the best for that.

Also lamium can get very thick especially the variegated one with the yellow blooms, good shade or part shade plant, don't know how it would be in full sun.

I'm out of ideas.

A few I have thougt of but have not tried.... German Chamomile, Creeping oreano and creeping mint. Those may be invasive though.

I like the alyssum idea...
Karen

These are all great - Thanks!

I have been looking all of these up for an hour now. I will update when I make my final choices. . .

I am in love with the Dianthus, Candy Tuft, Lamium and Creeping Thyme. Trying to match up colors and growing requirements right now.

And - the alysum is a great idea, too. I think cheap seeds had a huge quantity of it, so I could use it where ever I need it.

Invasive is an issue, isn't it? Right not I feel like it couldn't be worse than the weeds, but I know that those are famous last words.

But of course, you are talking to a person who grows mint on purpose, and actually *ran out* last year. That's only because we taught the kids to make faux-ijtos, though, and we had them every night after dinner, all 5 of us, lol. I am actually *adding more* mint this year! But it has it's own bed, surrounded by prison walls of cinder block.

Thank you for reminding me to WS my mint soon. Childhood memories of munching on the stuff, not sure what I'd cook with it but think it's used as a garnish. I guess it's where the spearmint flavor comes from, don't know what plant produces the peppermint flavor. I use peppermint oil occasionally but never spearmint, used to love those lifesavers.