There is not enough detail to confirm the identification of this species. So, as it's a gilled species I've put it under Agarics. The first image looked a bit like a Pleurotus, though the second with the two caps resting on each other made me think of Omphalotus nidiformis. These were around in April when you took the images. Also the centres appeared to have a light brownish-golden hue to them, typical of this species. Though this may have been shadowing or a photographic effect. If you see them again and they are near where you live try and get out and have a look at them at night to see if they glow!