Rattlesnake just was too bony for my liking. Frog legs are ok. I try everything at least once.
Chicken feet I just don't understand anymore than I understand pigs feet. It's all just mostly cartilage and such. I have tried both. I'd rather keep the chicken feet for stock. If I can ever find cow feet, I have a recipe from an old cookbook for cow's foot jelly I want to try.
I take all bones from the butcher for stock use. I have cooked marrow bones for eating, though. I have some antique marrow spoons.