Hi all,
None of them are really aquatic. I assume these aren't in the UK? but looking at the seed pods, the top/second/third one looks like Samolus valerandi, which occurs all over Europe, into W. Asia etc. in wet calcareous or slightly brackish conditions. It has definitely been sold as an aquarium plant, but I don't know how successfully long term. It grows around turloughs in W. Ireland, often out of rock crevices.
The Fern is an Adiantum sp. (Maidenhair Fern), they don't like being too wet at the root, but grew on damp rock faces etc . Assuming the rock is limestone, A. capillus-veneris would be likely.
I don't know what the moss is. The plant that looks like a Hydrocotyle is an Umbilicus sp. I think they all look pretty similar, but U. rupestris would be my guess. The seedling coming up in the moss is Stellaria media.
cheers Darrel