(1) "There are girls so cold-looking, pretty girls, too, ladylike, discreet, and armed with all accomplishments, whom to attack seems to require the same sort of preparation as a journey in quest of the north-west passage. One thinks of a pedestal near the Athenaeum as the most appropriate and most honourable reward of such courage. But, again, there are other girls to abstain from attacking whom is, to a man of any warmth of temperament, quite impossible. They are like water when one is athirst, like plovers' eggs in March, like cigars when one is out in autumn. No one ever dreams of denying himself when such temptation comes in the way. ... Phineas was not allowed to thirst in vain for a drop from the cool spring." (1869)
(2) "Sebastian lived in Christ Church, high in Meadow Buildings. He was alone when I came, peeling a plover's egg taken from the large nest of moss in the centre of his table.
"'I've just counted them,' he said. 'There were five each and two over, so I'm having the two. ...
"The party assembled. There were three Etonian [a large school near Slough] freshmen ... Each as he came in made first for the plovers' eggs ...'The first this year, they said. 'Where do you get them?'
"'Mummy sends them from Brideshead. They always lay early for her.'" (1945; the narrative is describing a February day.)
Having consulted Cocker and Mabey Birds Britannica s.v. Lapwing, I am confident that the 'plovers' were lapwings. See there for the evidence.
Sadly, this simple commodity is (like foie gras) no longer on the Waitrose list (memo try Fortnum's). A shame, because such watery fowl ... and their eggs ... might have counted as Fish. There is an Irish witticism to the effect that gannets used to be allowed in Ireland as Lenten fare, since their diet was exclusively piscine (I have always suspected that this is a joke kept up their sleeves by the Irish wherewith to gull gullible [geddit?] Englishmen like me).
BTW: I remember, I think in Maria Edgeworth, reading of a fowl called the 'Irish Ortolan'. Does anybody know what that was?