I think this is Ludwigia peploides 'Creeping Water Primrose', but there are a lot of Ludwigias in the database and Google photos as well, so I'm not sure. This is growing in the boggy edges and shallow (1"- 2") water in my stock pond as it dries up from lack of rain. I hope these photos are good enough.

The blooms all have 5 petals with that distinct green star pattern. About an inch in diameter or slightly more and just above the foliage - not on long stalks.


The stems are sort of pinkish/bronzy and creep along. It's not clumpy at all. Couldn't tell how many plants were growing as a result - one or many.


This is the clearest photo I got of the leaves and their structure.


This is a broad view of it growing. The blooms were really noticeable, but not dense.