Looks to me like its an eastern diamondback from your render. But the ones I've seen had a more 'woodsy' look. The largest I've seen was 5' 8" long with a 9" diameter. Texas is a strange place, kind of a mixture between eastern and western United States. Rattlesnake don't always 'rattle' before they bite. I know from first hand experience, stepped right over one and never saw it until it moved. I do skin em' if I find a fresh dead one and its not tore up too bad. They make great longbow decorations.

 Don't sweat the petty things, and don't pet the sweaty things!  ; )