I have found cactuses in California supermarkets (more precisely in Mexican one). Yes, you can see them also in California desert but here you can just buy and cook them. I found a recipe of nopales salad and nopales with eggs (nopales or Prickly Pear Cactus is the plant from the Cactaceae family): Mexico in my kitchen
Well, I guess I will try it once or better make Mexican friends who can cook nopales for me. Or even better - I will just invite my Mexican friends for dinner and will cook nopales for them:-)) To be continued.