Egg Dumping

Female quails have been known to participate in "egg dumping".

Picture from Tall Timbers

Egg dumping is where a female quail lays eggs in a nest other than it's own.  This is why sometimes you'll find a quail's nest with upwards of 25 eggs in it.  Typically a clutch (group of quail eggs) varies in size between 10 and 20 eggs.