Pretty!
I'd like to know what it becomes...

My guess is sweet autumn clematis. Mine always has some seedlings.

SAC does not produce any white patterning in the foliage. It also holds it leaves differently.

The plant looks to have square stems - if so it is a member of the mint family, Lamiaceae. Plants that have this appearance and have a somewhat climbing/spreading habit would include yellow archangel, Lamiastrum galeobdelon. This is not a vine per se - it does not have climbing abilities - but it will sprawl over and up into other plants. And can be very aggressive - listed as a noxious/invasive weed in many areas.

You're right, gardengal--I take back my guess of SAC. I should have looked at the enlarged photo before I guessed. (My SAC seedling leaves often have some variegation when the plant is young.)

My first guess was also yellow archangel, Lamiastrum galgobdelon. However, the variegation is reversed. That makes it a bit suspicious . . . .

Should I consider this a weed, and yank it? I am in Maryland as well. Thank you for any help.