In Little Miss Muffet what was she eating?

Curds and whey. Curds are a dairy product obtained by coagulating milk in a process called curdling. Whey is the liquid remaining after milk has been curdled and strained. The whole mess is similar to cottage cheese.
Little Miss Muffet was eating curds and whey. The curds are the solids of milk, and the whey is the liquid. Curds and whey occur in milk when rennet is added to cause the milk to curdle as part of cheese making.