“A best/good friend is like a four-leaf clover—hard to find, and/but lucky to have” is a friendship saying that has been printed on many images. “A good friend is like a four-leaf clover—hard to find and lucky to have!” was printed on a Care Bears porcelain plate in 1985.
   
“A best friend is like a four leaf clover, hard to find and lucky to have” and “Good friends are like four-leaf clovers: hard to find but lucky to have!” were both cited in print in 2001.
   
           
Wikipedia: Four-leaf clover
The four-leaf clover is a rare variation of the common three-leaf clover. According to tradition, such clovers bring good luck, though it is not clear when or how that tradition got started. The earliest mention of “Fower-leafed or purple grasse” is from 1640 and simply says that it was kept in gardens because it was “good for the purples in children or others”. A description from 1869 says that four-leaf clovers were “gathered at night-time during the full moon by sorceresses, who mixed it with vervain and other ingredients, while young girls in search of a token of perfect happiness made quest of the plant by day”. The first reference to luck might be from an 11-year-old girl, who wrote in an 1877 letter to St. Nicholas Magazine, “Did the fairies ever whisper in your ear, that a four-leaf clover brought good luck to the finder?”
           
Wikipedia: Care Bears 
The Care Bears are a group of multi-colored bear characters. The original artwork was painted by artist Claire Russell for American Greetings in 1981 to be used on greeting cards; but the characters were later used for toys, and in TV programs and films.
 
Amazon.com
American Greetings
Care Bears Lasting Memories 6 1/4 Inch Porcelain Plate - Good Luck Bear & Friend Bear “A good friend is like a four-leaf clover-hard to find and lucky to have!” 1985
   
Google Groups: misc.forsale.non-computer
“Care Bears” Collector Plate for sale
j.r. sinclair
7/4/95
FOR SALE;
I have for sale one (1) Care Bear’s Collector Plate. This plate features Good Luck Bear and Friend Bear “Lasting Memories”. This plate is gold trimmed and was produced in 1985. On the front of the plate are the two bears playing on a puff of cloud with a coloured rainbow overhead. Under the bears are the words “A good friend is like a four-leaf clover- hard to find and lucky to have!” (in script style writing).
   
Google Groups: alt.collecting
FS: Care Bear Ceramics
Michael and Delinda Roberts
2/20/97
The following are for sale, shipping is extra.
1.  Bedtime bear ceramic lamp, no shade, $15
2.  Care Bear plate, features Goodluck and Friend, says A good friend is like a four leaf clover—hard to find and lucky to have, 6 inch diameter, $6
 
29 March 2001, The Interior Journal (Stanford, KY), “Notes from Sara,” pg. 3, col. 2:
Thought for the week: A best friend is like a four leaf clover, hard to find and lucky to have.
   
8 May 2001, Indianapolis (IN) Star, :Let It Out,” pg. E2, col. 6:
Good friends are like four-leaf clovers: hard to find but lucky to have!
   
15 July 2001, News of the WOrld (London, UK), “Festival of hate shames our land” by Bishop Pat Buckley, pg. 11:
A best friend is like a four-leaf clover, hard to find and lucky to have.
   
Google Books
The Official Friends Book
By Martha Bolton
West Monroe, LA: Howard Publishing Company, Inc.
2003
Pg. ?:
A best friend is like a four leaf clover — hard to find and lucky to have.
Anonymous
 
21 July 2005, The Montana Standard (Butte, MT), pg. A5, col. 1:
In memory of
FRAN RADER.
A friend is like a four-leaf clover, hard to find, but lucky to have, and I had the best. I miss you so, my dear friend. Maureen.
 
28 March 2007, Miami (FL) Times, “People” by Anna Grace Sweeting, pg. 2C:
A friend is like a four-leaf clover: hard to find and lucky to have.
 
Google Groups: dhost
: Lovely - A friend is like…....
Varun Khanna
11/5/07
A friend is like…....
 
A friend is like
a four leaf clover,
hard to find
but lucky to have.
 
I am very lucky to have found a friend as good as you!
   
Google Books
Her Inspiration:
Secrets to Help You Work Smart, Be Successful, and Have Fun
By Mina Parker
San Francisco, CA: Conari Press
2008
Pg. 88:
A friend is like a four-leaf clover, hard to find but lucky to have.
SAMANTHA ROSALES
 
Twitter
Moe‏
@Cool_moeD
Replying to @iadorewomen_
RT @Martez_Truth A friend is like a four leaf clover, hard to find but lucky to have.
1:39 PM - 27 Nov 2010
   
Twitter
❥Black Roses…‏
@sacrifice_myluv
A friend is like a four leaf clover, hard to find but lucky to have.
11:18 PM - 29 Nov 2010
   
Google Books
Food For Thought:
A Collection of Quotes
By Pam Pottorff
BookBaby
2015
Pg. ?:
A best friend is like a four leaf clover: hard to find and lucky to have.
 
Twitter
gladene bautista‏
@gladene
A friend is like a four leaf clover, hard to find, lucky to have. 👭👬… https://www.instagram.com/p/BfTtBJdhaLRSx0bxA9y31iMx0BZ1iqcqw0LikY0/ …
12:28 PM - 17 Feb 2018 from Lipa City, Calabarzon