I have that plant, or something very similar. I got it and forgot to keep the info card or write down the name. I got it narrowed down to bacopa caroliniana (water hyssop) as the plant species available at the store I got it from is very limited and that was the only one that looked like my plant. I was looking for more of the same from another store and they had a similar plant with much bigger leaves than mine has. My leaves are 1 to 1.5cm long.