I don't have a clue what this is. It comes back every year and may be very old as the property is historic. Any ideas? Thanks.

Doh! Bouncing Bet!

yep
soapwort
but there are about 20 types
so what one

Flower color resembles Bouncing Bet (Saponaria officinalis 'Flore Pleno')

I planted one of these about 25 years ago. Since then it has been spreading like wildfire, but it never blooms. It makes a nice ground cover, but I would appreciate some flowers. Any ideas?

I dunno. Mine gets partial shade, and our soil tends to be acid. Miracid?

Mine has spread so much that it's in partial shade, full shade, and full sun, covering an area of about 12' x 20'. My soil has enough acid, I'm sure. The roses, irises, clematises, petunias, carnations, and trumpet vines in the same bed all bloom well. It's a real mystery.

It is unquestionably Saponaria officinalis 'Flore Pleno', double-flowered bouncing bet. ('Flore Pleno' means double-flowered. It doesn't refer to a flower colour but the normal colours are pink and white.)