New Zealand Truffle / Scarlet Berry Truffle (Paurocotylis pila)

New Zealand Truffle / Scarlet Berry Truffle (Paurocotylis pila)

Observation - New Zealand Truffle / Scarlet Berry Truffle (Paurocotylis pila) - UK and Ireland. Description: Found in the garden today. In relatively undisturbed soil below a young Oak and a well-established H

Found in the garden today. In relatively undisturbed soil below a young Oak and a well-established Holly. Bright orange-red appearing to become browner with age. Four specimens; three appeared still to be growing, the fourth loose on the surface. No stipe seen. Interior appears convoluted with some voids. Hopefully some spore detail to follow *. Size: photo 1 shows a standard sized ID card for comparison; a bit larger than a walnut. Easily cut. Pleasant, slightly mushroomy smell.
Not one I'm familiar with. Looking through Phillips the nearest I can see would be one of the Gyromitra fungi but some combination the environment, fruiting season and rarity - or all of the above! - would seem to rule them out. Any suggestions would be welcome.
Edit: * failed to recover any spores.