The term Wonderful Parliament refers to an English Parliamentary session of November 1386 which pressed for reforms of Richard II's administration.
Wonderful Parliament Wikipedia
Largely in response to King Richard's extravagant patronage of such favourites as Robert de Vere, and despite fierce opposition from the King himself, the Parliament resulted in the appointment of fourteen Commissioners to oversee Royal expenditure, and the removal of Michael de la Pole, Richard's Chancellor.
The Parliament is highly important in the context of later events: it marks the first stage in an ongoing power struggle between the King and a set of magnates who became known as the Lords Appellant.
Richard's defiant response to the Parliament, and attempts to convict its promoters of treason, ultimately led to the Battle of Radcot Bridge and the Merciless Parliament of 1388.
Even the deposition of Richard by Henry Bolingbroke in 1399 can be seen as a direct repercussion of this event.