I've had them pop up near my fish pond/hose bib area in my yard before....I usually seperate my seeds rite there though....I've never let them grow because it's literally my front yard/entry way ..lol...My friend usually carefully digs them up and grows them....or I murder them LOL.....The only issue I'd see with what you did is the soil...I would be super vigilant with how much you water. I like to build a super airy/fluffy soil to grow MJ in ...I've seen people grow in native soil and have stunted plants because of how compact the soil becomes....I'm not saying this will happen to you, it's just what I've seen with others over the years ....so good watering habits and get a good food schedule going IMO......I hope it turns out well for you GL with your experiment .....any weed is a success in the end GL