Nice of the speaker to let us know where we stand from the get-go—no need to guess where the action takes place, though there's no guarantee that we'll actually end up in Rochester, Minnesota. In fact, if this is a car trip (and who doesn't love a car trip?), it seems to have stalled for the moment by the side of the road.
Twilight bounds softly forth on the grass.
Nice of the poet to let us know the time of day, too. It's twilight, but this twilight isn't just a time of day between afternoon and night. This twilight appears to be a personified creature of some sort, capable of leaping softly (like a deer? like a panther? like a person?).
Hmm… in the space of two lines, the poet has deftly shifted from mundane realistic details to a personified concept. Time to sit up straighter in our chairs and pay attention, because this speaker bears watching: no telling where the poem will go next!
And the eyes of those two Indian ponies Darken with kindness.
Aww… the poet has led us to ponies. And not just ponies, Indian ponies. And not just Indian ponies, kind Indian ponies. Does the term "Indian ponies" refer to a particular breed of horse, or does the speaker mean that the ponies are owned by Native Americans? Let's file that question away for the moment and keep our eyes peeled for further evidence.
In these lines, that twilight creature (no, not a vampire) seems to have faded into the background, as we make contact with two living, breathing animals in the natural world. Of course, one might argue that "kindness" is a human trait, projected onto the horses, rather than an actual trait of the animals. But any reader who owns a pet is likely to take issue with that point of view.
They have come gladly out of the willows To welcome my friend and me.
The poet is not backing off from that kindness idea; the words "gladly" and "welcome" reinforce the idea that the ponies are kindhearted. In these lines, we also meet the people who are meeting the ponies: the speaker ("me") and a "friend." Maybe these were the folks on the road trip, the ones who pulled off the highway. If so, did they stop just to stretch their legs, or did they pull over specifically to meet these ponies?
Line 5 provides a little more information about the setting. In addition to the grass mentioned in line 2, there are trees, and not just any old trees, willow trees.
Again, the poet is using a realistic detail to invite us further into the poem. Notice that "willows" and "welcome" begin with the same letter. Is that fact merely a coincidence, or does the alliteration of these two words carry some special meaning? (If you're curious, check out the "Sound Check" section.)