Oxalis stricta, called the common yellow woodsorrel, common yellow oxalis, upright yellow-sorrel,lemon clover, or more  ambiguously and informally sourgrass or pickle plant. Herb, weeds.
Home - Garden
Should You Plant A
Clover Lawn?
By DANIEL FEININGER
Improve Soil Fertility
The benefits of planting clover interspersed throughout your lawn are wide-ranging and positive. Clover uniquely provides enhanced fertility and nitrogen content to improve your soil's health, while also being highly tolerant to trampling, grazing, and cutting, and it does well in both the flowering and colder seasons.
Suffocate Weeds
Clover works with a grass-based lawn because it requires little watering, no fertilizer, and kills off weeds with ease. The root structure descends beyond the root layer of your grass, meaning that it won't compete with the grass itself, but will be a barrier that won't allow weeds to grow.
Add Unique Beauty
Besides weed control and fertility, clover will also beautify your lawn in a way that's sure to turn heads. Clover remains green deep into the winter, and then blooms in spring to incorporate a variety of tiny flowers that add depth and texture to the beauty of your lawn and home.