People say “Season’s Greetings!” at the end of the year. A sheep riddle was printed in 1993:
 
“QUESTION: What do sheep say at Christmas?
ANSWER: Season’s Bleatings.”
 
A pun on the classic Christmas blessing, “Peace on earth, good will to men,” was posted on the newsgroup alt.humor.puns on December 9, 2000:
 
“As shepherds like to say, ‘Fleece on earth, good wool to men.’ (Richard Lederer)”
 
A group of puns was posted on the newsgroup alt.humor.puns on December 21, 2004:
 
“Shepherd’s greeting: Season’s bleatings. Fleece on earth. Good wool to men. (Richard Lederer)”
     
 
Wikipedia: Annunciation to the shepherds
The Annunciation to the shepherds is an episode in the Nativity of Jesus described in the Bible in Luke 2, in which angels tell a group of shepherds about the birth of Jesus. It is a common subject of Christian art and of Christmas carols.
(...)
Translational issues
The King James Version of the Bible translates the words of the angels differently from modern versions, using the words “Glory to God in the highest, and on earth peace, good will toward men” (where the word “men” is used generically to mean “people” or “human beings”). Most Christmas carols reflect this older translation, with It Came Upon the Midnight Clear, for example, using the words “Peace on the earth, good will to men, / From Heaven’s all gracious King.”
     
Google Books
The Silliest Joke Book Ever
By Victoria Hartman
Pictures by Robert W. Alley
New York, NY: Lothrop, Lee & Shepard Books
1993    
Pg. ?:
QUESTION: What do sheep say at Christmas?
ANSWER: Season’s Bleatings.
       
Google Groups: alt.humor.puns
“Puns of the Weak” 12/08/00
Stan Kegel
12/9/00
As shepherds like to say, “Fleece on earth, good wool to men.” (Richard Lederer)
 
Google Groups: alt.humor.puns
Kids Puns of the Weak 12-21-04
Stan Kegel
12/21/04
(...) 
Shepherdąs greeting: Season’s bleatings. Fleece on earth. Good wool to men.
(Richard Lederer)
     
Google Books
December 2007, Boys’ Life, “Think & Grin,” pg. 69, col. 1:
Bob: What kind of holiday card does a sheep give?
Joe: I have no clue.
Bob: Ones that say “Season’s BLEATINGS!”
Cristopher Steineman, Glen Carbon, Ill.
 
19 December 2007, The Daily Mirror (London, UK), “Greg’s giggle” by Fiona Parker, pg. 41:
‘WHAT do sheep say to shepherds at Christmas time?
Season’s Bleatings.’
 
Twitter
gretchen smith‏
@gretchen_smith
What do sheep say to shepherds at Christmastime? Season’s Bleatings!
7:48 AM - 17 Dec 2009
 
Twitter
❤️ FizzyDuck ❤️‏
@FizzyDuck
What did the sheep say to Santa at Christmas? Seasons Bleatings! #lamejoke #xmas
1:21 PM - 22 Dec 2009
 
Twitter
Denise L‏
@MumsInstincts
@SodaStreamUK What do sheep say to Santa?Seasons bleatings! #FunnyFizzmas
9:58 AM - 23 Dec 2010
   
Twitter
hiding inside a book‏
@hiddeninbooks
what do sheep say 2 shepherds at christmas
seasons bleatings
2:48 AM - 27 Nov 2011
   
Twitter
andy cosstick‏
@heycos
Fleece on earth, and good wool to men! #christmasjokepunchline
5:25 PM - 26 Dec 2012
 
Twitter
The Film Cell‏
@TheFilmCell
What did the sheep say to the shepherd? Seasons Bleatings! #FilmCellCrackers #JOKE #Christmas #jokeoftheday
9:50 AM - 6 Dec 2013
 
Twitter
Baker & Taylor UK‏
@BakerTaylorUK
What did the sheep say to the shepherd?
Seasons Bleatings!
2:16 PM - 20 Dec 2013
     
Google Books
Christmas Cracker Jokes
By Amanda Li
London, UK” Pan Macmillan
2014
Pg. ?:
What did the sheep say to the shepherd?
‘Season’s bleatings.’
 
Twitter
Candi Dawn‏
@justgrits1
@FoustBrow What did the sheep say to the shepherd?
Seasons Bleatings!
6:09 PM - 12 Dec 2014
   
Twitter
Swan Upping‏
@SwanstonRobert
What did the sheep say to the shepherd?
Season’s Bleatings!
8:47 AM - 27 Dec 2016 from Islington, London
 
Twitter
Swan Upping‏
@SwanstonRobert
#sillysaturday
What did the sheep say to the Shepherd?
Seasons bleatings.
5:57 PM - 15 Dec 2017