This plant is growing in the Freeport roundabout which is planted with regional native plants, but the soil came from an agricultural field. We have been able to ID all the other "weeds" that have shown up, but cannot ID this one. It appears to be a member of the buttercup family. We only have the leaves to go by as we don't want it to flower and go to seed. Photo taken on October 2, 2015. Thanks for any guidance you can give me!
Stephenson County Illinois
Does this appear to be a vine? Look around the area and see if you can see it growing up any trees or fences. It looks to me like it might be a native plant, Parthenocissus vitacea- Woodbine, or the closely related Parthenocissus quinquefolia - Virginia Creeper. It usually has the 5-part leaf, but also has other numbers of leaflets, especially when the plant is young, as this one appears to be. Take a look at the photos here and see how your samples compare. If you don't think that it's Woodbine, then please upload a couple of photos with a better look at the leaves, please.