I wonder if EP says “half truth”, which could be later explained? “At the movies” could be “sitting in the basement, at home movie theater, watching the movies”. So if no one doubts, they are at the local cinema. But if checked seriously, “home, watching the movies”.
Likewise, she might have bought something in the Asian store, but not mushrooms at all. In our local Asian chain store, one can buy food, household items, cleaning products, makeup, even glassware. For all I know, she could have bought a wasp killer.
The beauty of buying some “Chinese herbal remedy” is that you have no clue what’s there. Years ago, before I visited dad, I’d go to a local Chinatown store and buy something for dad’s neighbor. Some Chinese remedy against alopecia, and he claimed that was the only one that ever worked. In hindsight, I’d think, it was finasteride, since it worked. But, in a different bottle, with Chinese hieroglyphs, it looked mysterious.
So Erin could have well bought something in her grocery store, but not mushrooms. In a package with Chinese letters, who can tell what it says, and she can later claim, it was a mistake. If I were LE, I’d check what types of rat poison local Asian grocery stores might sell, for example. Or herbicides, or something along the same line. Because I wonder if this is what she bought, and told half-truth.