Four leaf clovers in my garden

Happy St. Paddy's Day!

I know this is not the greatest photo but if you look carefully, these are truly four leaved plants. Colloquially called water clover, I've found they adore water and shade. This week, they are growing in a pot in my community plot but I'm considering bringing them back to balcony living since it's getting a bit warm and sunny. I wasn't sure what they were until I spied some at the United States Botanical Garden near the Smithsonian in DC, a fascinating place to visit, btw. The ones at the US Botanical Garden hailed from Australia, ironically enough, as wikipedia indicated there are a few species native to North America. Here's more on what wikipedia says about this family. I was surprised to find they are actually ferns, which is why I have been waiting in vain for flowers in order to ID them. Note, I don't know which ones I have.
Family: Marsileaceae, Marsilea sp. probably