Could be any of American Sparrows. I have seen Chipping Sparrows, Song Sparrows, and American Tree Sparrows that could match your description.
Individual bird links:
Chipping Sparrow:
http://www.mangoverde.com/birdsound/spec/spec202-268.html
American Tree Sparrow:
http://www.mangoverde.com/birdsound/spec/spec202-267.html
Song Sparrow:
http://www.mangoverde.com/birdsound/spec/spec202-291.html
For easier time ID'ing this bird of yours, please give us more detail, such as bill shape and size, maybe a photo if possible, anything, Even change you location ("USA") to something more specific, like City, State (Due to many species being year-rounders in one part of a state and never in another part of the state), that can help us.
Could also be a House Finch adult female, or Purple Finch adult female. There are tons of American Birds that match your description.
NOTE TO ALL NEW MEMBERS POSTING IN ID FORUM: Please help us help you. Without your descriptions and/or photos, we can't help you. Please be as descriptive as possible. Even if you think that a certain feature on your bird is a feature on all birds, it is of utmost importance to us that you tell us about the feature, no matter what. Descripbe the bird's appearance, action, feeding habits, what type of terrain you saw it in, where the bird was found, was it at a feeder, etc... Don't leave anything out.
Whew!
Anyway, DOUBLEJK, If you follow everything above, we might just be able to help you out quicker than without a photo or a concise description.