joe...
According to the clever 'History of Sampling' java applet
designed by Jesse Kriss, the first well-known musician to
use a record sample was Fred Wesley and the Horny Horns in
1977, in 'A Blow For Me, A Toot To You', taken from the 
Funkadelic's 'Good Ole Music', of 1970.
And the earliest well-known recording used for a sample was
Eddie Fisher's 'Beautiful Things' from 1952, used in the 
Beastie Boys recording 'Get It Together' in 1994. Enjoy:
http://jessekriss.com/projects/samplinghistory/
The article, 'The Art of the Sample', by n.h. zed, on the
website of The Museum of the African Diaspora, notes:
"Jesse Kriss is a programmer and musician who has created an
 interactive visualization of the network between the samples
 used in Hip-hop records and their original sources."
More on the page:
http://www.moadsf.org/seed-view.php?id=65814
A related article from that site by n. h. zed, co-authored
by Jesse Kriss, titled, 'A Digital History of Sampling',
explains the layout of the java applet:
"Each square represents an album, with sampled artists on
 the lower half and sampling artists on the upper half.
 Albums are placed horizontally according to release date,
 while vertical placement reflects the number of samples
 on that album. The middle resprents the area of most
 sampling, so commonly sampled albums are closer to the
 side with the sampling albums, and vice versa."
Clicking on a sampled album shows the links to the albums
that took samples from it, and lists them on the left.
Clicking on an album that used samples shows which albums
the samples were taken from. Click in a neutral space to
restore the default view.
Albums are also color-coded according to style:
- funk/soul/r&b
- jazz
- rock/pop
- other
Jesse also notes, in that article:
"One of the things that really grabs me about DJ culture
 is the element of history and education. DJs are often
 historians and link-makers, building on a previous
 generation of culture to create something new. There
 seem to be striking similarities to master drummers
 in certain African cultures ? the music is a key to
 communication and education."
More on the page:
http://www.moadsf.org/seed-view.php?id=22755
Sample data for the applet project was derived from
The (Rap) Sample FAQ site:
http://the-breaks.com
That site acknowledges the following books as sources:
Soul Music: Who's Who. Tee, Rick. Prima Publishing,
Paperback. 1991 
Rock Albums of the '70's, a Critical Guide. Christgau,
Robert. Da Capo, Paperback. 1981 
Rolling Stone Album Guide. Edited by Anthony DeCurtis
and James Henke with Holly George-Warren, Reviewed by
Mark Coleman, J.D. Considine, Paul Evans, David McGee. 
http://the-breaks.com/sources.html
You asked for well-known samples, but this answer wouldn't
be complete without a mention of an earlier, lesser-known
musician who used samples to the extent that some consider
him one of the fathers of pop music sampling, as noted in
this article on Reference.com:
"In the 1950's, Bill Buchanan and Dickie Goodman released
 a song, 'The Flying Saucer (Parts 1 and 2)', which featured
 samples of various then-popular songs, all taken out of
 context from their original material and used as answers
 to a wacky reporter's question about spaceships from another
 planet. Goodman would later make a career out of similar
 'break-in' or 'snippet' records, including such recordings
 as 'Mister Jaws' and 'Energy Crisis '74,' and is today
 considered one of the fathers of pop music sampling."
http://www.reference.com/browse/wiki/Sampling_(music)
More on Dickie Goodman here:
http://www.reference.com/browse/wiki/Dickie_Goodman
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