kidneyleaf buttercup, Ranunculus abortivus

One of the smaller buttercups, the flowers aren't quite a quarter inch across. Also called (more obviously) littleflower buttercup, or (less obviously) littleleaf buttercup, or (what the . . . ?) littleleaf crowfoot. Turns out crowfoot is an older and less catchy name for buttercups, and others in that family. They tend to have palmate and often lobed leaves. This one is a native with weedy habits in every state except AZ, CA, HI, NV, OR, UT, all provinces, and on SPM. Lenawee Co MI, 5/6/19.