I have lots of opuntia (prickly pear) species that I grow in pots. The only thing I would be worried about is the glochids, the tiny little hair like spines on the fruits and on most paddles themselves, getting stuck in the cockroach. I've pulled hundreds of them out of my hand and it's very painful (especially barbed cholla spines). I suppose there is a way to make them edible as people commonly use them in cooking, but I would be very careful.
I have a pot of the spineless opuntia that I used to feed a uromastyx, it was the only thing it would eat. The good thing is the 5 acres I live on is an overgrown hay field. And since I am an exterminator, there are no pesticides used any where on the property. I refuse to use anything at home. Must wash my hands a million times after I get home lol.
I would avoid feeding any part of the Sassafras plant. All parts of the plant contains Safrole, which is toxic and carcinogenic. Roaches may be able to tolerate it fairly well, but if you are using them as feeders, that could be an issue. Here is a link - https://en.wikipedia.org/wiki/Safrole
Thanks, I have decided to avoid wild food do to possible pathogens that could be passed to the herps. I just lost some recently wild caught gulf coast toads to a ridiculous worm load. So I will not be taking any chances with my new pacman frogs.