I think I know what you mean now, Barb. Not the metal, spring toggle bolts, but the plastic ones that expand the "wings" as you tighten the screw. I've seen those, but don't know/remember what they are called. I think they came with something in a mounting hardware bag. Yeah, those are pretty good fasteners. I wouldn't even know what to ask for if I had to get them.
The one you mentioned, Joe, I am much more familiar with. Those things rock. And you can knock them into the drywall with a semi-hard rap of your hand on the screwdriver. Yep, they hold a lot of weight.