I am not sure if there are two different types of fungus or just one. The first two photos had fungi of large diameter (largest was the size of a saucer). The last two photos were the size of a 20 cent piece). The smaller fungi were situated a few metres away from the larger ones.
I agree Fiona that you have two different fungi. Those large ones that are forming a tier have gills that run down the stem (stipe) and their general looks makes me think these are a species of Pleurotus. Whereas the smaller ones don't have this obvious characteristic and there appears to be some brown/rust colour coming in their gills which makes me think these might be a Crepidotus
These are great images. Would you be able to separate them and put those smaller ones up as a different and additional sighting and I will identify it accordingly.