Mysterious seeds being mailed out to people across Canada and the US may be part of a brushing scam.

Unsolicited packages are showing up in people’s mailboxes, most of which contain seeds.

The Canadian Food Inspection Agency is warning people not to plant the seeds as they may be invasive species that could easily overwhelm local landscapes.

Kristen Matthews of the Better Business Bureau says the reason seeds are being sent out is because they are light and inexpensive to ship.

She says the packages, from China, are often labeled as jewelry or electronics, but usually contain seeds.

Matthews says brushing scams are about artificially boosting online reviews for certain products.

She says they’re carried out by third party sellers on Amazon, eBay and other e-commerce platforms that require reviews on fulfilled orders. Those names are then used to pose as satisfied customers through fake, glowing reviews.

Another concern is that the scammers are somehow gaining access to names and addresses in order to ship their product out.

Anyone who receives an unusual or unsolicited package through the mail is asked to report it to the BBB Scamtracker.