Are all 8 cauliflowers the same variety?

I am new to growing cauliflower myself so take this with a grain of salt.

What variety of cauliflower did you plant? If it is one of the white headed types it is recommended to blanch the heads (wrap the outer leaves over the developing head and secure with some elastic) as they grow to keep the suns rays off of the head. Too much sun can cause loose and discolored head development but you did not mention what type of weather you are currently experiencing other than a lot of rain recently.

I'm still waiting for my Cheddar cauliflower that was transplanted out 2 months ago to start forming heads.

I bought a punnet of 8 seedlings from a local store that were labelled as simply being "large white", so assume they should be the same.

I've read about the tying of leaves to blanch the heads, but didn't bother as I thought it was to prevent sun scald, and there's been no chance of that, as we hardly saw the sun in the last few weeks. I must do that faithfully next year!

And maybe get a couple of more interesting varieties to try, too. But a badly home grown cauliflower still tastes 100% better than a store bought one...

The cauliflower leaves are also quite delicious cooked, and those in the picture are beautiful! My only thought on the head was that either it was overripe or it should've been blanched.

Sherm...they certainly weren't over-ripe, so I reckon it must be the lack of blanching and/or excess rain.

Yes, perfect leaves, and on the broccoli as well. I collect both and cook stuffed "cabbage" rolls. So much tastier than any cabbage I've eaten.