Scales are not found on Rhizopogons. Another point for searching elsewhere for an identification. Endoptychum can have scales, but should also have an identifiable stipe, which I cannot see here.

There’s always a chance you found one of the hundreds of species now known from Oz, but not well understood yet.

Yes, these were found in a plantation of Pinus radiata.

I probably won’t be able to get back there any time soon but will keep an eye out for them next time I’m in a pine forest.

They had a spongy texture if that helps.

No locules present. So cannot be Rhizopogon.

Scales support something like Endoptychum, but no stipe present.

REALLY need mature specimen for this one, I’m afraid. Keep checking, please?

The sectioned specimen does seem to have an oddly expanded sterile base, much wider on one side than the other. May still be an odd form of puffball as you originally suspected. Knowing what species of pine this is with could help as well. Maybe Monterey pine (Pinus radiata)? I believe this species was introduced widely to Australia and New Zealand both.