Is it yellow rattle seed that will take over from grass and spread like a flower lawn?
All sorts of wild plants pop up in our garden. I dig up the St. John’s wort and anything highly toxic/invasive but most plants I leave alone. Love in a mist has somehow seeded all around the pond, along with rock cress, creeping thyme, wild geraniums, wood avens, creeping buttercup, marsh marigold, creeping jenny. Many of these have grown up through a very thick weed membrane the previous owner installed and covered with slate chips. Wild plants do find a way! There are some massive ferns, a bleeding heart bush, periwinkle, many types of flag iris near the water. I’ve made a corner of chopped log pieces from when we had a tree trimmed, they mulch down eventually and provide habitats for insects. Those insects in turn attract birds, frogs etc.
We have grass that’s rather lumpy and yellow but I let it grow longish in between mowing. I think lush green lawns are over rated unless you use a lot of chemicals and weed killers.
Our neighbour has astroturf. His garden looks neat but rather bare; all their plants are in pots and he has to vacuum the ‘lawn’ and power wash it!
Nothing I plant seems to grow apart from mini conifers and winter flowering heathers, so I wait to see what arrives on its own each spring!