Hi Alan,

This is a species of Ranunculus (common name - buttercup). There are several species it could be including Ranunculus bulbosus or Ranunculus acris, but without further inspection I can't make a positive ID. Regardless, fresh buttercup plants are toxic to grazing animals, who can suffer from salivation, skin irritation, blisters, abdominal distress, inflammation, and diarrhea. Fortunately, buttercup has a strong, bitter taste so animals generally try to avoid it if more palatable forage is available.

They are typically found in over-grazed pastures. As such, populations can be reduced by promoting healthy grass by overseeding, fertilizing as needed, and not over-grazing.

In terms of control, mowing before the flowers turn to seed can help reduce populations. Broadleaf herbicides can be applied over grassy areas infested with creeping buttercup to selectively kill the buttercup and not the grass.

More information on control can be found here: https://extension.wvu.edu/lawn-gardening-pests/weeds/buttercup