@Shell, not quite enough detail in this pic to determine species, at least to my eyes. You should be able to tell by looking closely in person. C. erecta's 3rd petal has 2 points, like an upside-down V. There's also usually a slight fuzziness on the sheath that covers the flowers. A native in USA.
Day flower (Commelina erecta)
The other option would be C. communis. It's 3rd petal comes to a single point, and has a little brown dot in the middle of the 2 larger yellow things. Not native in USA.
Asiatic Dayflower (Commelina communis)