"The well of the grain is in Meadon, that is, a well from which grain flows without ceasing. There is in the same district a well from which the bones of birds are constantly thrown up."
Although the "well of the grain" seems associated with the underground quern of Mauchline, it is also in the same district as the well of bird bones. All suggestions for bone wells in Scotland welcome. It seems, for the moment, as if this one might be lost.
There is a "Boneywell" spring near Richard's Castle near the Welsh border. This is three miles from an area called Marestun c.10861, which could be "Meadon". The spring was a well-known tourist site in the 1700s, and was still throwing out frog or fish bones then, but has since been much reduced.
You can read more on the Science of the Boneywell, along with Visit Details, and some old tourist images of it in Myth.