Probably hawkbit, but might be cats ear, they're difficult to tell apart without seeing the leaves. There'll be a rosette of dandelion-like leaves on the ground.
We've got an old hay field that never gets any sprays on it. Hawkbits are fairly common but don't cause any problems. I'm presuming they're not poisonous because one year a visitor mistook them for dandelions & made a bucketful into wine. He didn't get any side effects apart from the usual confusion and falling over that one expects from home made wine.
