http://www.foragingtexas.com/2008/08/greenbriar.html
A common edible wild plant. From the web page:
Greenbriar is one of the best wild foods available as it can be found in immense quantities all year-round, tastes really good, is very nutritious, and is a source of calories (tubers). Greenbriars are the only vines that have both tendrils and thorns making them easy to identify.