Hello, Pavlo, In addition to weeds, unwanted or random flowers can show up from seeds spread by wind, birds, and wildlife. Here in So. Calif. I have had Queen Anne's lace, columbine, and sunflowers sprout from volunteers. In Ukraine, you probably have a different selection. Some common ones for your area might be: orange hawkweed, marigold, common broom, thistle, mugwort, bindweed, yellow flowered lamium, and Sosnowsky's hogweed which is a serious skin irritant.
I had a wonderful time translating names of plants from english into english and then finding their equivalent here! Bindweed and mugwort do grow everywhere along the roads here. It is not considered to be plants at all. It is a wild grass here