Oh-so-pretty describes a common plant now appearing in gardens and on forest floors in the months of April, May, and often into June. The yellow flowers are shiny and strongly resemble buttercups, to which they are related.
Lesser celandine Ranunculus ficaria is an ephemeral ground cover, meaning that after its period of bloom both the flowers and the heart-shaped leaves disappear. Don't be fooled by this. The tubers of this plant will simply wait underground until next winter when they will gradually send up new leaves and begin the cycle again. They also reproduce by achenes - small, dry, one-seeded fruits easily spread by birds. Thus you will see even more of the plants. Their rosettes will be everywhere: in your gardens, in your perennials, in your grass.
Lesser celandine is an exotic introduced species that competes with native species. How, you ask? Lesser celandine completes most of its life cycle early and thus shades out many native species. It does this by "getting there first," before trout lily, Dutchman's breeches, bloodroot and other spring ephemerals emerge from the floor of our forests. Got it? Dig it up carefully being careful to dig under the tubers, which are numerous. (By the way, I did find a use for this plant. The flowers and leaves make beautiful pressed plant specimens.)
What about marsh marigold, a relative of lesser celandine? Marsh marigold, Caltha palustris, is a native species which grows in wetlands. The flower stalks are about six-to-eight inches, unlike those of the shorter lesser celandine. It doesn't compete with other species, doesn't form a mat, and has no tubers.
I would bet that you probably have mouse ear chickweed growing somewhere in your gardens as well. It is so common that gardeners tend to simply yank it out without much thought. This is a member of the pink family (You are probably familiar with duckweeds relative, the garden dianthus, especially the carnations.) Mouse-ear chickweed is hairy and forms mats if left undisturbed. The little leaves are opposite each other and it is so shallow rooted that it is easy to remove. Chickens love it, thus the name. The flowers are white and have five petals but this looks like ten because they are notched. It is edible and foragers use it in salads. You are welcome to do this as well, but not if you are using herbicides or insecticides on your property. If the weed bothers you, note that it tends to die down in the hotter months.
And then there is purslane, also called pusley or pigweed. The leaves are succulent. I have never seen purslane growing in a lawn but it can be quite prolific in gardens where the soil is disturbed by cultivation each year. This weed is a relative of the beautiful Portulaca that you can grow from seed or purchase for your gardens. Purslane grows in poor soil as well as humus rich soil and spreads quite quickly. Its fruit is a capsule, which explodes and sends the seeds in all directions where they lie in waiting. It always "welcomes" me home from vacations and time away from the back garden.
I am presently experimenting with organic corn gluten as a preventative to the purslane seed germination; I will keep you posted on this. Purslane is actually quite edible and is good in salads, so you can always explain its presence in the garden by referring to it as "garden greens."