I am not positive about what weed you are talking about  and there is no image but I can guess you mean yellow buttercup. This weed thrives in damp, acid soil with poor drainage. Using lime on your lawn and garden will make the soil less acid and discourage this weed. The problem is it can take years to slowly change the pH or acidity of the soil using agricultural lime. On my lawn I applied lime (a product called Super Sweet) in the spring and in the fall at the rate recommend on the bag and I saw less buttercups after three years. A much quicker fix is to improve the drainage with sand and a layer of sandy loam right on top of the lawn and to aerate every year to improve drainage.  Adding dolomite lime also helps to break up clay soil and improve drainage so you can do both - lime every year at least once and raise the level of your soil so it sits above the water line to improve drainage. Keep growing, Marianne Binetti