Historically, the cento is ancient. Early Greeks built poems from such works as The Iliad and The Odyssey. Roman poets composed centos taken from the works of Virgil, and Renaissance poets worked with lines from Petrarch and Cicero. Modern cento forms include variations (i.e., a single borrowed line that’s echoed throughout a poem), and today’s centos are often witty or ironic.
Be sure to read “The Dong with the Luminous Nose” (a cento by John Ashbury that takes its title from Edward Lear and includes lines from poems by Gerard Manley Hopkins, T. S. Eliot, and Lord Byron, (http://dougkirshen.com/dong/start.html), and "Ode: Salute to the New York School 1950-1970 " by Peter Gizzi, http://www.jstor.org/pss/20132337).