My garden has been full of this weed (pictured) this year. Can anyone tell me what it is and how to prevent it from coming back in the future?
That might, possibly, be Virginia Creeper, a plant that is widely spread by birds eating the seeds and then dropping them all over the place. Because of that pulling is the single best means of control. Herbicides might work on growing plants but do not prevent germination of seeds in the furture.
Here is a link that might be useful: About Virginia Creeper
I don't think it's Virginia Creeper, unless the juvenile form is utterly different than the adult. However, it doesn't really matter what it is - just start pulling it up before it sets seed. If it's hard to pull up, use your pitchfork to loosen the roots.
There is really no way to prevent weeds from showing up, as long as there are birds flying overhead and pooping as they fly. All we can do is pull up the weeds and mulch if possible.
Good luck with weeding; believe me, we all share your pain; for me, it's onion grass and pokeweed.
No, it definitely isn't Virginia Creeper. The Name That Plant Forum can probably id it for you. As lisanti07028 says, get pulling before it seeds.
it is called Mulberry weed and I have been fighting it for the past year. I pull them up every time I see one but the only thing it does is give me satisfaction... it really doesn't control them very well.
Here is a link that might be useful: Mulberry Weed: Identification and Control