Your trim is LS. That means that you could have had wheel covers, or that you actually do but don't know it. Some of the offerings were steel wheels with chromed plastic covers that look just like the real deal, but they're glued on. Hitting them with enough force, such as by being curbed, can break the cover and/or the glue, causing the kinds of sounds you've described.
If you curbed a wheel, that usually means that you hit a vertical curb with the wheel, leaving a noticeable scratch on the wheel or wheel cover.
If it was more like hitting a pothole, then you might have tire damage, more likely in the sidewall. If so, expect a bulge to start showing on either or both sides (inner & outer).
If you curbed it with the inside of the wheel then you may have bent the dust shield, which can be bent back fairly easily.
Otherwise, the crunching could be small rocks or pieces of concrete embedded in the brake pad material that are making that sound as you get closer to stopping.
If you can't find it yourself or with friends, you may want to have a shop look at it. A brake repair or tire seller might do, or your dealership.
