In the "Little Miss Muffet" rhyme, the titular character is said to sit on a tuffet, which can be seen either as a tufty clump of grass or a small stool similar to a pouffe. However, because Miss Muffet is said to be frightened away from her seat by a spider, it may be safe to assume that, in this context, the referenced tuffet is a clump of grass rather than a piece of furniture.
While a vague answer to this question is given in the second verse of the Mother Goose nursery rhyme ("as much wood as a woodchuck would chuck if a woodchuck could chuck wood"), a more precise answer — according to a 1995 study — is that woodchucks can chuck 361.9237001 cubic centimeters of wood per day. According to the Scientopia blog, a study focused on answering this question was published in the magazine "The Annals of Improbable Research" in 1995. Groundhogs, which, according to National Geographic, are also known as woodchucks, were used as the subjects of this study.