In the back of the Norton Critical Edition of Malory are a bunch of direct sources from 15th century England. In particular a sequence of letters between two families about the ownership of a particular property.
(The argument in these letters would eventually lead to the last battle between private armies on English soil.)
I have cleaned up the spelling but tried to keep the rest of the language intact. At the bottom of the letters are a bunch of isolated terms which you should be able to use with any word processor to customise the letters to any D&Dish campaign. This could be an argument between any two noble families in a pseudo-European setting.
The letters could be recovered separately in treasure hoards or on the bodies of murdered curiors, or their delivery could be the object of quests. The context they imply is effectively an adventure on its own, or just rich background for a world. If read out the language is quite a bit more interesting than the customary boxed text.
As events start, Lord T has occupied the manor of Wotton for some time. Lord B claims Wotton and his wife is in the capital trying to press the claim legally.
LETTER ONE - LORD B'S WIFE TO LORD B
(To my right honourable and reverend lord and husband be this letter delivered.)
Right honourable and reverend lord and husband, I commend me to you with my whole heart, desiring always to hear of your good welfare, the which God maintain and increase ever to your honour.
And if it please you to hear how I fare: Thomas Roger and Jacket have asked surety of peace from me, for their intent was to bring me into the Tower. But I trust in God tomorrow that I shall go in bail until the next term, and so go home, and then to come again.
And sir, I trust to God, you will not treat with them, but keep your own in the most manliest wise, you shall have the land for once and all.
Be well ware of Venebles of Alderley, of Hugh Mull, and your false council; keep well your place. The Viscount Lisle lies right near you and shapes all the wiles that he can to distress you and yours, for he will not meddle with you openly no manner of wise, but it be with great falsedom that he can bring about to beguile you, or else that he cause that you have so few people about you; then he will set on you, for he says he will never come to the King again till he has done you an ill turn.
Sir your matter speeds and does right well (save my daughter costs right good; at the reverence of God send money, or else I must lay my horse to pledge and come home on my feet).
Keep well about you till I come home and treat not without me. And then all things shall be well, with the grace of almighty God who has you in his keeping. Written at London the Wednesday next after Whitsunday.
Isabel, Lady Berkley
LETTER TWO - LORD T TO LORD B
William, called "Lord Berkley," I marvel you come not forth with all your carts of guns, bows, with other ordinance, that you set forward to my manor of Wotton to beat it down upon my head.
I let you know, you shall not need to come so near for I trust to God to meet you near home with English men of my own nation and neighbours - whereas you by subtle craft have blowing about in diverse places of England that I should intend to bring in Welshmen for to destroy and to hurt my one nation and country; I let you know I was never so disposed, nor never will be.
And to the proof hereof, I require you of knighthood and of manhood to appoint a day to meet me half way, there to trial between God and our two hands all our quarrel and title of right, for to eschew the shedding of Christian mens blood - or else I shall meet you.
An answer of this by writing, as you will abide by, according to the honour and order of knighthood
Thomas Talbot the Viscount Lisle
LETTER THREE - LORD B TO LORD T
Thomas Talbot, otherwise called "Viscout Lisle" - not long continued in that name but a new-found thing brought out of strange countries - I marvel greatly of your strange and lewd writing, made I suppose by your false, untrue counsel that you have with you, Hugh Mull and Holt: as for Hugh Mull, it is not unknown to all the honourable men of this Realm, how he is convicted of falseness and the raising of the King's records; and as for the false mischievous Holt, what his rule has been to the destruction of the Kings liege people in my lordship of Berkley, as well as to the hurt of their bodies and the loss of their goods, against Gods law, conscience, and all reason, is openly known - so that every honourable man should refuse to have them in fellowship - and also of his own free will, undesired of me, before honourable and sufficient witness, was sworn on a Mass book, that he never should be against me in no matter that I had ado, and especially in that untrue title that you claim, with which you withhold my livelihood wrongly.
And when you require me of knighthood that I should appoint a day and meet you in the mid way between my manor of Wotton and my castle of Berkley, there to try between God and our two hands all our quarrel and title of right, for to eschew the shedding of Christian mens blood, or else the same day to bring the uttermost of my power, and you would meet me: as for the determining of between our two hands of your untrue claim, and my title and right of my land and inheritance, you know right well there is no such determination of land in this realm used. And I ascertain you that my livelihood, as well as my manor of Wotton and my castle of Berkley, be entailed to me by final record in the Kings court by the advice of all the judges of this land in these days being.
And if it were so that this matter might be determined by your hands and mine, the King our sovereign lord and his laws not offended, you should not long desire but I would as soon answer you in every point that belongs to a knight: for you are - God I take to record - in a false quarrel, and I in a true defence and title.
And where you desire and require me of knighthood and of manhood to appoint a day, and that I should be there with all the power that I could make, and that you will meet me half way, I will you understand I will not bring the tenth part that I can make - and I will appoint a short day to ease your malicious heart and your false counsel that is with you: fail not tomorrow to be at Niblyes Green at eight or nine of the clock, and I will not fail, with Gods might and grace, to meet you at the same place, you who stand in the borders of the livelihood that you keep untruly from me, ready to answer you in all things, that I trust to God it shall be showed on you and yours to your great shame and dishonour.
And remember yourself and your false counsel have refused to abide the rule of the great lords of this land, which by my will should have determined this matter by your evidence and mine: and therefore I vouch God to record, and all the company of heaven, that this fact and the shedding of Christian mens blood which shall be between us two and our fellowships, if any happen to be, does grow of your quarrel and not of me (but in my defence and in eschewing of reproach), and only through your malicious and mischievous purpose, and of your false counsel and of your own feeble discretion.
And keep your day; and the truth shall be shown by the mercy of God.
William, Lord of Berkley
SEARCH AND REPLACE
Lord B's first name - William
Lord B's surname - Berkley
The first name of the wife of Lord B - Isabel
Lord T - Thomas Talbot
Title of Lord T - Viscount Lisle
A lawyer of Lord T - Hugh Mull
A second lawyer of Lord T, Surname - Holt
An agent working for Lord T - Thomas Roger
A second agent working for Lord T - Jacket
A secret ally of Lord T - Venebles of Alderley
Title of a (presumed male) Ruler - King
Name of a God - God
Name of a famous prison - the Tower
Name of a Capital City - London
A holy book or object - Mass book
A day of the week - Wednesday
A religious festival - Whitsunday
Name of the disputed property - Wotton
The place appointed for a duel or battle - Niblyes Green
Name of a 'good' home nationality - English
Name of the same good home nation - England
Name of a 'bad' neighbouring nationality - Welsh
Name of a religious or ethnic group - Christian
You may wish to replace in a medieval setting - guns