Lonchura striata
The white-rumped munia (Lonchura striata) or white-rumped mannikin, sometimes called striated finch in aviculture, is a small passerine bird from the family of waxbill "finches" (Estrildidae). These are not close relatives of the true finches (Fringillidae) or true sparrows (Passeridae). It is native to tropical continental Asia and some adjacent islands, and has been naturalized in some parts of Japan. Its domesticated descendant, the society finch or Bengalese finch, is found worldwide as a pet and a biological model organism.
Source: Wikipedia
Other members of the waxbills and allies family recorded in North America — a useful place to start if you are not certain of your identification.
You don't need to spend a fortune. These four pairs will get you birding confidently on day one.
From phone adapters to dedicated rigs, here's what actually works for capturing birds in the field.