Suggestions: don't look at new Corollas.
Shop for a good used Corolla. Their styling hasn't changed enough to notice, but your mom will sure notice how you kept things well under budget. Besides, going used means that you may be able to opt further up the scale of included Corolla equipment - a loaded new one goes for well over $20K, but a loaded 3-year-old one goes for well under.
Really want to impress Mom? Get a good used Camry. Roomy, practical, not at all suggestive of zippy driving or young foolishness - but it's a good car you can drive for years and years and years.