From the photo you sent, it looks slightly raised. Usually when we see growth patterns like this, it's due to a variation in the soil. These variations are sometimes caused by old foundations for ornamental structures such as bird baths or could indicate that a tree or flower bed was previously in that location. Sometimes it is due to fungi feeding on decaying organic matter in the soil, such as old stumps or tree roots. These types of circles are called fairy rings and can sprout mushrooms.

https://hort.extension.wisc.edu/articles/fairy-rings/

Usually if it is a fungal disease such as necrotic ring spot, the ring will be brown, not raised and green.

https://www.canr.msu.edu/ipm/diseases/necrotic-ring-spot