Without a pic my first guess is bridal wreath spirea (super arching branches if the shrubs are left natural), There is also exochordia, and maybe Philadelphus. And try looking up pics of deutzia.

Hope that helps. Megan

Probably Chinese Dogwood, Cornus kousa.
Do they look like this?
Mike

Thanks to both. It appears to be bridal wreath..

I must have skimmed over "the bigger ones are 12 to 15' high".
Mike...putting up with a lot of distractions.

Focus, Mike, focus!