Bacopa moneiri ?
I doubt it. B. moneiri has leaves that are closer to spatulate, with no petiole, and somewhat thickened, slightly succulent.
Not reniform with long petiole and thin blade.
Not an actual ID, but this single leaf looks like Dichondra.
Please, more pictures including how the leaves are attached to the stem, flowers or fruit, and growth habit.
Bacopa moneiri is a pond to marsh plant, has opposite leaves and a 5 petalled flower that is usually close to white with a hint of purple. It will grow under water in a well lit aquarium, and flower when it reaches the surface.