I found a single sock, covered in dust on my stairs earlier. Definitely does not belong to anyone in my house, nor does anyone in this house have a reason to cart around random dusty socks. Ive hidden it because it has freaked me right out.
Could it have been found near your house and brought in my someone. DH is for ever bringing the pint glasses the drunks from the local pub leave on our windowsill in until I noticed our ever expanding pint glass collection and made him stop it.