Some folks keep an immaculate lawn and use herbicides to keep the grass free of weeds and anything not grass. My lawn is lucky to get mown once a week, and yes weeds are in it, but some of them are interesting to look at up close. Here is a short description of several wildflowers that are classified as lawn weeds. Some of the blooms are quite small, so get down and take a close look.
Violets (Viola species): These are well known and easy to identify. They can be purple, white, yellow, or mixed colors. All have an extended lower petal that is described as “lipped” in identification manuals. Most have heart shaped leaves, but one in my yard is called Field Pansy, and has spoon shaped leaves with tufts of blunt narrow leaves that are called stipules. The flower is white with some yellow in the middle.
Purple dead-nettle (Lamium purpurium): This one is very common, especially where the grass is thin. It has small purple flowers and heart shaped leaves that overlap and form a whorl around the top of the plant. The top leaves are usually purplish, and the flowers are tube-like and “lipped”, having that extended bottom petal. Dead-nettle is in the mint family and so has a square stem.
Henbit (Lamium amplexicaule): The flower is the same as dead nettle, but the leaves are more rounded with a blunt toothed edge. The leaves form in opposing pairs and clasp the main plant stem. Leaves and flowers form at intervals along the stem, not clustered at the top like dead-nettle. The plant tends to grow along the ground with the ends growing more upright. It is also a mint with a square stem.
Dandelion (Taraxacum officinale): Needs little description and is the bane of any lover of pure grass. Still, it is handsome when in bloom, and if you wish to make lemonade out of lemons you can eat the leaves as a cooked green (before blooms appear).
Chickweed (Stellaria media): There are several varieties but common chickweed is usually the one in lawns. It grows along the ground and has small oval leaves that occur in pairs. The flower is small, white, and daisy-like, with 5 petals that are split, so it may look more like 10 petals.
To enjoy wildflowers more, consider investing in a good wildflower I.D. book.