SuttaCentral
What early Buddhist text(s) do you wish more people knew about?
I would especially invite folks who have never posted before to join in.
Maybe don’t quote the whole sutta, but give us a snip. Also remember if you just type the citation, like MN1 it will automatically get turned into a link.
Oh gosh! This is like sutta nerd catnip. I really look forward to seeing other people’s responses. It’s going to take me a while to decide on just one or two.
SN12.23 for sure! 
One of my favourite canonical stories is in Thag 10.4, about a monk who was likely neurodivergent by today’s standards. Buddha gives him a towel of some sorts, and tells him to meditate on it. And through this practice he reaches enlightenment.
One of those interesting quirks from the canon. 
My progress was slow,
I was despised in the past.
Even my brother turned me away,
saying, “Go home now.”
(…)
The Teacher, out of sympathy,
gave me a foot-wiping cloth, saying:
“Focus your awareness
exclusively on this clean cloth.”
After hearing his words,
I happily did his bidding.
I practiced meditative immersion
for the attainment of the highest goal.
I know my past lives,
my clairvoyance is clarified;
I’ve attained the three knowledges,
and fulfilled the Buddha’s instructions.
If you are open to “non-canonical” you can get the whole story in the Dhammapada commentary.
I’ve always loved MN21, from the moment I first read it, for several reasons:
I remember when I first read this sutta, many years ago now, and I didn’t know much about the Dhamma back then, but when you read it (and actually any sutta from the similes section of the middle length discourses), you don’t really need to have a lot of background knowledge because the Buddha was very skilled in transmitting his teachings via similes and communicating profound concepts in a language suitable to the audience present.
Whenever I feel like I’m feeling a bit ‘puffed up’ , I only need to bring to mind the story of Vedehika, and remind myself that just because I’m not feeling any negativity right now, it doesn’t mean that my underlying tendencies have been eradicated, it’s a humbling reminder.
Wonderful quote from the sutta:
‘Our minds will not degenerate. We will blurt out no bad words. We will remain full of sympathy, with a heart of love and no secret hate.’
And as Bhante says as an intro to the sutta:
This is my contribution 
Inspired by Gabriel’s answer, I’ll throw in a lesser known liberation sequence in AN10.76 Three Things.
and the Nibbedhika Sutta AN6.63 , though I feel this is better known. I love the verse about sensual pleasures.
The Roots of Everything.
Translation by Bhante Sujato: AN 10.58 The title that Bhante has landed upon is ‘Rooted’. Now then. I didn’t understand the Australian connotation of this word until fairly recently. Very good Bhante.
Here’s a (somewhat unorthodox) and very loose translation of the key parts from some of my very old dhamma study notes:
All things are rooted in desire.
They come into being when attention is paid.
They originate through sensory contact,
and come together as sensory experience.
Headed by stillness, all things are
overseen by mindfulness.
The highest of all things is understanding.
At the core of all things is freedom.
They culminate with freedom from death,
and are ended by extinguishment.
A translation by Bhikkhu Bodhi is also available at SC
Can you explain please for those of us who are even slower?
No. Absolutely not. Not in polite company
Oh my goodness! 
Where the mind jumps towards sometimes….
I think this is probably my first post here after having been on the site for a year. Thanks for inviting people like me to post. The one discourse that I wish everyone knew is the first sermon SN56.11 because it lays out the entirety of what the teaching is about - the Four Noble Truths and the Eight Fold Path. (I am aware that there is a debate on what really was included in this sermon originally.)
I thought I somewhat understood the core of buddhism and was practicing it before arriving to the point in my life where it occurred to me that may be I should read the actual discourses. I started my journey by reading the first three sermons. What surprised me after reading the first sermon was that it clearly defines dukkha, an otherwise untranslatable word. I realized that it does not need to be translated, instead people need to be pointed to its definition as is given in this sermon. It dawned on me what else was there that I thought I knew but don’t.
I was also in a shock for a week about how clear, precise, and concise the sermons are - not a surprise given that they were composed for recitation. The line defining dukkha is also beautifully rhythmic.
There was no going back to reading interpretations and commentaries for me after this unless they are scholarly analysis of the EBTs.
I have many favorite suttas, for a variety of reasons. The latest addition to my list of favorites is SN 12.65, “The City”. It’s the sutta where the Buddha explains how he discovered dependent origination and awakening! 
And the more I am reading this text, the more it gives me goosebumps!
Thanks to Bhante @sujato and Ajahn @Brahmali for teaching this course on dependent origination which I’ve been recently studying!
I should think for most of us, it’s nearly impossible to state a singular favorite or most overlooked Sutta. But, I always come back to Thag 12.2 Sunītattheragāthā, The Verses of Arahant Sunīta.
A victim of an oppressive caste system, Sunita is the scavenger/street cleaner of (flowers/ or feces) “Shunned by people, I was disregarded and held in contempt. I humbled my heart
and paid respects to many people.”
Sunita encounters the Buddha, who “being sympathetic,
and having sympathy for the whole world, said to me, “Come, monk!” That was my ordination.”
Sunita practices with dedication, and becomes an Arahant. His experience embodies, to me, the heart of Buddhadhamma: you can begin from any place or station, and with dedicated and heartfelt practice, find release.
Who said anything about just one? Oh, I guess I did in the title. Let me fix that.
Keep 'um coming!
Generally, ‘rooted’ is used when we are trying not to be as rude though.
I have many favs, but this one is the first one that gives me hope:
“… good qualities flow on and fill up from one to the other, for going from the near shore to the far shore.” AN 11.2
When I find that the far shore is very far, I’ll come back to this sutta to remind myself that the first step is not too difficult after all (and stop thinking about the advanced difficult steps!)
I find MN86, really inspiring.
The Buddha saw him coming off in the distance, and said to him, “Endure it, brahmin! Endure it, brahmin! You’re experiencing in this very life the result of deeds that might have caused you to be tormented in hell for many years, many hundreds or thousands of years.
It’s particularly helpful to read and contemplate when I am feeling regret over past unskillful behaviour (thankfully not to that extent) or facing self doubt in my abilities to practice. We all have to start somewhere right ?