Pestle puffball (showing guttation?)

[Saxon-lady]

Hi everyone, I’m new to mushrooming, but wonder if any of you knowledgeable guys could give me a definite id on this mushroom patch growing in my garden please? They started popping up white but have darkened, and are white spongy inside, smell of shop-bought mushrooms, but the more mature ones are green and mushy inside. 
 

I notice also, that the mature ones are oozing red or yellowish liquid when I squeeze them. Is this red liquid guttation? (You can faintly see it on the second-to-last pic.)

Not intending to eat any - just curious! 

Appreciate any advice, cheers guys.