Ranunculus ficaria is known as the common buttercup or lesser celandine. These annoying little weeds come from temperate Eurasia and North Africa and come up as a spring ephemeral so you can miss them. If you see them get them now before they flower their little solitary yellow flowers and disappear.
An invasive perennial weed Ranunculus ficaria has heart-shaped leaves and smooth leaf margins (edges). The leaves might have a little white mottling in them, and are only an inch or so in diameter.
They grow in clumps anywhere from 1" to a few square feet. They are shallow-rooted and spread thanks to tons of little bulbs and bulblets. The bulbs are a very helpful ID characteristic in the spring garden.
Because of how many bulblets the plant can make remove the plant in its entirety and try not to shake them. Put them right into plastic bags in the garbage, do not add to your compost pile!