I found these growing on a roadside, near a ditch with water. Any clue what they are?

Kathy, I don't know what it is but the flowers look to be of the mustard family. The leaves don't look right for mustard, maybe some one else will be able to tell for sure.

Could it be Dame's Rocket, which is actually a member of the mustard family? Flowers could be blooming early if you had a warm winter (like we did).

The leaves look right for Dame's Rocket, alternating and toothed, also four petal flowers.

Here's a link about Dame's Rocket (Hesperis matronalis)
http://www.illinoiswildflowers...

There's another similar plant, Lunaria annua which has also naturalized in USA.
Money Plant (Lunaria annua)

Leaves don't look like Lunaria as I grow it here.