Any Idea what this weed might be? It was reported in a drain ditch.
Very hard to tell without a sample laid out clearly on a piece of contrasting paper. Your idea of some type watercress is a good one. Compare the plant to the photos here---
And descriptions here---
Watercress is a non-native plant that is invasive in some areas. As always, never eat any plant you haven't positively identified. You may send samples to MSU Diagnostic lab for positive ID--- https://pestid.msu.edu
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