This natural looking hole has appeared, I think, as a result of an underground spring coming to the surface due to a blockage, then returning underground again. A similar occurrence happened at my father's house twice over a period of 40 years after heavy rain.
Uploaded to Geograph by Dave Spicer on 14 February 2010
Photo © Dave Spicer, 14 February 2010. Licensed for reuse under this Creative Commons licence