Barnyard Grass.

Is it safe to assume that the silence from the forum means that my plan makes sense and is on track? :D Was really hoping to hear from someone! :)

I have these in my yard, they seem to be perennials. Amenable to being mowed, digging out the taproot is needed to remove. Mowing often enough so that new seeds are not formed/dropped will stop the spread of new plants, and this one does bloom again quickly after being mowed. Your post does not include your location but your "lawn" looks similar to those in my area. The "weeds" provide better ground coverage than the vine-like grasses that constitute a lawn in this area like Bermuda, St. Augustine, torpedo, bahiagrass, centipede. If your interest lies merely in having some kind of soft greenery instead of bare ground on which to walk and play, there is no need to be concerned about the non-grass plants within the mowed areas. There is a lawn forum here if it is your desire to try to cultivate a monoculture of grass.

No.1 is not clematis (nether is the last one).....that is very likely poison ivy. No.2 is Virginia creeper, Parthenocissus quinqefolia, and people who have a sensitivity can develop a strong reaction to this plant as well....contact dermatitis.....just not to same the degree as poison ivy produces. So it IS - or certainly can be - a problem! btw, if you want fast and accurate plant or weed ID's, post your question in the Name That Plant forum. That is it's whole purpose!! One of the most active forums on this website :-)