If you need help in tracing sources for historical research in the early common law then a new wiki may be just the help you need. Hazel Lord, Senior Law Librarian at the University of Southern California, has set up English Medieval Legal Documents AD600-AD1535: a compilation of published sources. 
Its goal is to be a “collaborative database on the published sources … [re documents in this period] .. and to provide links to the growing number of online sources.” (Click scope for further details.) Its ambition is to keep growing, but already it is a invaluable tool with items in the following categories already: Case Law – The Courts, Statutory Law – Legislative Records, Administrative Law – Records of State, Private Legal Documents – Wills, Writs and Pleadings, Early Legal Treatises, Collections of Texts from Various Sources, Online Sources, Research Guides & Bibliographies, Histories, Author List, and Title List.
And the answer to where to find that elusive Eyre? In Maitland, Frederic W., ed. Three Rolls in the King’s Court in the Reign of King Richard the First. A.D. 1194-1195. 2 Vols. (1891). Not yet online -but the wiki has the link OCLC: 2511172 which does the next best thing, taking you through to WorldCat so you can find a library near you which holds the volume.
