The mysterious seeds that have turned up in mailboxes across the United States have been identified.

According to the U.S. Department of Agriculture, a number of the packets — which appeared to have originated in China — contain mixtures of mustard, cabbage and morning glory seeds, while others contain a mix of mint, sage, rosemary and lavender seeds. The news comes after state officials warned residents against planting the seeds, fearing they were sent as part of a plan to introduce invasive plants to the U.S.

USDA officials believe the seeds were actually sent out as part of a “brushing scam,” which involves sending unsolicited samples of a product to someone and then posting a bogus positive review from the receiver.

Source: https://www.cbsnews.com/news/china-seeds-usda-investigation-identified/