Your picture is a bit small, but it appears to be a Kalanchoe, probably Kalanchoe blossfeldiana.* These are tropical plants and don't do well in temps below 40*F.* I grew up in the Catskill Mtns. and I'm sure your night time temps have already dipped close to that.* You will need to bring in your plant and hold back a bit on watering at first as these plants are succulents.* Take a look at these sites to see if my id is correct.
You can do a google with the full botanical name and click on 'Images' for better id.* Here's how to move plants indoors and outdoors.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.