to come fluttering in (e.g. leaves, snow, flowers, etc.); to come dancing in
to drop in unexpectedly; to happen unexpectedly
窓から雪が舞い込んだ。
Snow drifted in through the window.
縁側から虫が舞い込んでいる。
Bugs are fluttering in through the veranda.
思いがけない仕事の依頼が舞い込むことがあった。
Unexpected job requests sometimes came dancing in.