Another look...

And a picture of the bottom leaves...

Perhaps bittercress or a near relative.

In any case, pull & discard NOW before those elongated seed pods fling their seeds in all directions.

They are annuals and will die soon. But they fling out thousands of seeds and those seeds will start sprouting next fall and grow through the winter. Then next spring you will see them again....

Whether these are "weeds" or flowers depends on your perspective. If they are a plant that you do not want growing where you do not want it to grow then it is a "weed". In another place and with another gardener these might be considered flowers.

I think that one is Wintercress, a taller relative of the also P-I-A- Bittercress.