Her expression is perfect. "How could this have happened? It was a flawless crime if you ignore the trail of incriminating evidence I left at every point."
All she needed to do was say she picked them thinking they were wild mushrooms, and she didn't eat much because she was upset at her ex not attending. It would have just been another misadventure story. Instead she failed to give any answers at all, which is what made everyone so interested in the first place.
Still wouldn’t have added up as she was known by the community to be an experienced mushroom collector. Death caps don’t look like any edible Australian mushroom, and they only grow in symbiosis with oak trees. They’re very easy to avoid.
Almost all the accidental death cap poisonings that occur in Australia involve people who’ve arrived from China relatively recently. Death caps can look very similar to edible Chinese straw mushrooms. This is why it’s important to learn the local flora/fauna, as it may be different to what you grew up with.