More than a dozen types of seeds have been sent from China to people across the United States, with no indication as to why. Most species were identified as innocuous herbs but officials have advised not to plant them due to fears of them being invasive or harmful to humans.

So far, the United States Department of Agriculture (USDA) has identified 14 kinds of seeds, including flowering plants like morning glory, hibiscus, and roses, vegetables such as cabbage and herbs like mint, sage, rosemary, and lavender. All 50 states have issued warnings about the packages.

“We don’t have any evidence indicating this is something other than a ‘brushing scam’ where people receive unsolicited items from a seller who then posts false customer reviews to boost sales,” USDA said in a statement. “USDA is currently collecting seed packages from recipients and will test their contents.”

The seeds have so far arrived in white packages with Chinese lettering and the words “China Post,” with some labeled as jewelry, according to images shared in social media. USDA is now collecting the packages and will test their contents to see if they could damage agriculture or the environment.

MDA is aware that people across the country, including in Maryland, have received unsolicited packages of seeds from China in recent days. MDA is working closely with its partners at @USDA_APHIS to monitor this situation. (1/3) pic.twitter.com/x6GiVyoUj4

— Maryland Agriculture (@MdAgDept) July 27, 2020

Anyone who receives such packages with seeds from China shouldn’t plant them, the USDA said in its statement, asking for citizens to contact their state plant regulatory official and keep hold of the seeds and packaging, including the mailing label, until they receive further instruction.

Robin Pruisner, an official at the Department of Agriculture in Iowa, told Reuters that the seeds could be coated with something, possibly insecticide or fungicide. “I’ve had people describe to me that the seeds are coated with something purple. I haven’t had it in my hands yet, but it sounds an awful lot like seed treatment,” she said

Meanwhile, Sid Miller, the Texas agriculture commissioner, warned the packages could have harmful invasive species or be otherwise unsafe, according to a press release. Invasive species are organisms not native to a certain region that can cause the destruction of native crops and introduce diseases.

“An invasive plant species might not sound threatening, but these small invaders could destroy Texas agriculture,” Miller said in the release. The Texas Department of Agriculture “has been working closely with USDA to analyze these unknown seeds so we can protect Texas residents.”

Lori Culley from Utah told Fox News she found two small packages in her mailbox that appeared to contain earrings. “I opened them up and they were seeds,” Culley said. “Obviously they’re not jewelry.” Culley said she posted about the strange incident on Facebook, and “at least 40 people” reached out to her saying something similar happened to them.