The link above is a page on cactus recipes. It says all opunita species
are edible (non-toxic). It says the prickly pear cactus is the state
fruit of Texas! Of interest to the current discussion...
"Texas A&M in Kingsville, TX has done extensive work on a cultivar
designated as the 1308 which is spineless, resists cold weather and
contains less mucilage."