This is an illustration of Earth and the Roche limit
for various satellites. I created this image to
discuss the possibility of rings around Earth. The
smallest circle represents the Earth itself. The
other two circles have their centers at the barycenter
of the Earth/Moon system, which is the point about
which any rings would orbit.

The smaller of the concentric circles is the Roche
limit of something having the same density as the
Moon. The outer of the concentric circles is the Roche
limit of something like a comet. Rings would probably
appear from the Roche limit outward to 2 or 3 times
the Roche limit. It is my opinion that the presence
of the Moon, and hence the wobbling of Earth would
make the presence of such rings impossible except
over a very short time frame.

Furthermore, since Earth's rotation is inclined with
respect to its orbit and Moon's orbit is inclined
with respect to both of these, what would happen is
that the rings would quickly disperse into a cloud
that would probably orbit over all of the tropics.