Smoke rising from ground near Mill Race Road home

We're out to the area of (number withheld) Millrace Road.

Again, (number withheld) Millrace Road.

Caller is not home, but received a call from his neighbor stating that there is some sort of smoke coming up out of the ground between.

(number withheld) and the neighboring property.

I don't know what it's coming from or what it is.