I went back and looked at the original photos and enlarged them on my screen and found what I was looking for. I am going to say it is Senna marylandica. The pistil of S. hebecarpa has long white hairs, where S. marylandica has short hairs the lay flat. You can see in this crop from your picture that there are few hair visible. The pistil is the long green curved part, between the dark anthers.
Here is a pic of S. hebecarpa showing how long the hairs are on the pistil.
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