The consensus is that brushing explains the seeds, but the writer of the article researched it pretty thoroughly and disagrees. He thinks what really happened is people ordered the seeds via Amazon and then forgot about their order and were surprised when the seeds arrived.
That sounds far fetched but guess what—when he contacted several people who reported receiving mystery seeds and had them pull up their Amazon purchase history, all of them had indeed placed an order and forgotten about it. In fact, one of the people was the gardener lady in England who got the ball rolling on the whole seed thing when she posted about it to her online gardening group. She too had forgotten about her order.
The writer is now hoping that more mystery seed recipients will see his article and contact him so he can have a bigger sample to test his theory. Maybe he’ll do a follow-up with the results.
Or... Amazon could be gaslighting people, placing legit looking orders in people’s purchase history, even though the people never ordered them. Then, the people create a fake memory to explain the order being in the history.