This is something in the Solidago clan I think. Nonetheless, it is not any Buddleia because the stem will never get woody.

I was thinking it might be a goldenrod, but the ends have suddenly bloomed with distinct but small white flower. I'll post a pic when I get one.

Here is a photo of the flowers. There are poppies and other things around it though the tall skinny plants in the background are from this mystery.

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The flower appears to be something in Brassicaeae, the mustard family.
Can you give us an area in which you are taking photos? This may help in the ID. ( which state)

Should have mentioned, I'm in Minnesota. I took a look at a plant database here but it doesn't seem to match any of them.

I took some detail shots.

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The flowers of the plant in the original photo do not appear to have fully opened yet.

The white flower is a different plant. It has alternate leaves while the other one has opposite leaves. I agree it is probably something in the mustard family

Yup, two different plants. The flowered one is shorter. The more I look at it the more I'm thinking it's a galium. The taller of the two looks like it's about to bloom which should solve the problem. These are in the ornamental native garden I started this year so I'm trying to keep an eye on what I need to pull before it seeds.

What a difference a couple of days makes. The mystery plant has bloomed. I've been looking online but can't find it. The flower was not at all what I was expecting. Blossoms are less than a half inch tall.

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Linaria, perhaps.