This plant started popping up behind my garage and it's growing out of control. What is it, and what should I do about it? I live in Ohio.
It's Lamium galeobdolon, commonly known as Yellow Archangel or deadnettle. The latter name is because the plant resembles common nettle, which stings, but Lamium has no sting. Classed as a wild flower or a weed, depending on whether you want it growing or not! You can dig it out, or remove some of it, if you want. Does well in shady places, but, as you can see, it can be rather invasive.
Lamium galeobdolon ‘Variegatum’ sometimes called aluminium plant although it has many other names, and there are other plants called aluminium plant too.
In some areas it is classified as an unwanted or noxious plant and in such cases should be removed if possible. The problem with it is that it creates a dense covering that prevents the growth of native seedlings and other plants.
In other areas, you can deliberately buy it as a ground cover or to use in hanging pots. It is particularly useful as a ground cover in shady areas, as it can be hard to find good plants for those conditions and this one grows well and looks pleasant.
See this site for information on removal if desired King County, Washington .gov