I was at the in-laws for a day on the weekend and found my little guy with this plant.Most lily pads I've seen have a definite 'start' and 'finish' to the leaf - at 11:40, the edge clearly folds into and at 12:20, it bulges out again, showing apparent endpoints. Not this leaf.
They grow in swampy water, like lily pads, but the stalk is strong enough to carry the leaf well above the water.
Finally, do these look like frog eggs or the like? I have heard of some frogs that glue their eggs above the water, so that the tadpoles dive into the water upon hatching.
The visit with the in-laws went well, with me managing to not embarrass myself in helping with the farm-work. I helped plant about twenty rows of potatoes, each row around 200 metres long - with the whole extended family, it took around four hours.