While walking the Lady Bird Trail, I came across quite a few of these Yaupon Holly Trees. They are native to central Texas among a few other places. They are often grown in residential landscapes and make great ornamental twigs around the holiday seasons. The leaves and twigs contain caffeine, which American Indians used to drink in homemade teas. You must have a male and female plant to have berries
Source: http://www.wildflower.org/plants/result.php?id_plant=ILVO
iNaturalist Observation: http://www.inaturalist.org/observations/4391724