Whom did the poet meet at the close of the day in "Easter 1916"?

In "Easter 1916," the speaker mentions the rebels he used to meet at the close of day, or in the evening, after they presumably were leaving their workplaces. The rebels were part of an armed rebellion in Dublin that rallied together to oppose British rule and start a new Irish Republic. They were just normal people for the most part, as the speaker says in this first stanza: laborers, common workers, and passionate, political free thinkers. In the end, they were executed. As the first four lines of the poem explain, the speaker remembers their "vivid faces" emerging from behind "counters" or "desks" among the "grey, eighteenth-century houses" of Yeats's own Dublin neighborhood: "I have met them at close of day/Coming with vivid faces/From counter or desk among grey/Eighteenth-century houses." These normal, hardworking people, who soon became brave rebels, were not initially respected by the speaker.
The speaker explains that he never had any genuine, meaningful interactions with these rebels; they were insignificant to him. He reiterates this idea by saying that if he had conversations with them in passing, or if he stopped to talk to them at all, the conversations were filled with "polite, meaningless words," and he repeats this twice just to drive his point home.
The speaker seems to have been passing the rebels on the way to his club, where he would tell a "mocking tale or [take]a gibe/To please a companion/Around the fire at the club." Here, Yeats may be talking about meeting friends at his Dublin version of The Order of the Golden Dawn, because he had joined this offshoot of freemasonry in London and helped to found the Dublin Hermetic Order. He was in the order with another poet, Aleister Crowley, whom he is known to have feuded with.
The order can be described as a cult where men socialized and practiced alchemy, magic, seances, and other occult rituals. Such secret orders are oftentimes elitist, and witchcraft by nature assumes superiority by seeking to exert control and personal will over the world and people around it. The tone of this part of the poem definitely reflects Yeats's feelings of superiority. A "gibe" is a mocking insult, and "motley" refers to jester clothes. In a nutshell, at whatever club he was attending after passing the rebels, Yeats would talk about them as if they were a joke and mock them with insults.
Of course, their brave stand against British oppression may have shaken Yeats into thinking he underestimated these common people, as they later are referred to as immovable stones in a rushing river. The "terrible beauty" referred to at the end of this stanza is an oxymoron, most often read as a tribute to the beauty of their attempt to change the course of an oppressive history and the terrible end they met.