These are worth browsing through

Various Medieval texts,

http://etext.lib.virginia.edu/collections/languages/english/mideng.browse.html

Including; The Towneley Plays, 32 15th century mystery plays

In Full, http://etext.lib.virginia.edu/toc/modeng/public/AnoTown.html

Some Background information

http://www.ucalgary.ca/~scriptor/towneley/

Langland, The Vision of Piers Plowman

http://etext.lib.virginia.edu/toc/modeng/public/LanPier.html

Chaucer, Canterbury Tales

Original and modern translation side by side

http://www.fordham.edu/halsall/source/CT-prolog-para.html

Various, from Wikisource

http://en.wikisource.org/wiki/Category:Medieval_poetry

Middle English Literature

http://www.luminarium.org/medlit/

and Middle English Lyrics

Texts http://www.luminarium.org/medlit/mltexts.htm

and explanatory notes, http://www.luminarium.org/medlit/lyriclinks.htm