Japanese quail (Coturnix japonica) are shy & very well camouflaged in the wild, It's rare to spot them on the ground & tend to only get noticed when they explode from cover like a squadron of harrier jets.
One could say they are, to use birding terminology a typical LBJ (little brown job).
 Kept tame & well lit by flash even the wild form shows their true beauty & are far from plain.
The above male who was very camera curious shows just how attractive these birds really are.

& his mate (above) shares the same multi hued & patterned plumage but lacks his showy breast & has a speckled breast instead.

Like a lot of once wild birds that have been kept domestically for centuries, man has bred for different plumage colourations & mutations.
The Golden Italian (below) is probably the second most common after the wild & shares the same marking but in a much lighter sandy tone.

Another popular form is the English white.  As its name suggests just plain white although almost all birds have a spot or two of brown usually on or around their heads.  Not as easy to tell the sexes apart but the males have more facial feathering which they use when showing off to the girls. Many breeders prefer white birds for the meat trade as with other poultry & game, the odd feather left on a white bird after plucking doesn't show as much as with darker plumaged birds.

The Spanish or Range quail is a melanistic  form.  Much darker & with completely different markings to the wild & Italian.

 Finally the Pied or Tuxedo.  Another melanistic type but with white breast & facial markings.
A very striking bird in my humble opinion.

These are by no means all of the plumage variations out there.  I have owned cinnamon, & there are also blue mutations.  As they are all the same species cross breeding & the resultant variety can be very interesting.  With certain genes being dominant & others recessive you are never sure what might turn out.
As always right click & view image to see full sized.