These are irregular past-tense forms that we would not expect to hear before the more regular forms. However, they do typically precede the appearance of the -ed inflection. Once the regular past-tense forms (walked, played) begin appearing in the child’s speech, the irregular forms may disappear for a while, replaced by overgeneralized versions such as goed and comed.
For a period, the -ed inflection may be added to everything, producing such oddities as walkeded and wented. As with the plural forms, the child works out (usually after the age of four) which forms are regular and which are not. Finally, the regular -s marker on third person singular present-tense verbs appears. It occurs first with full verbs (comes, looks) and then with auxiliaries (does, has). Throughout this sequence there is a great deal of variability. Individual children may produce “good” forms one day and “odd” forms the next. The evidence suggests that the child is working out how to use the linguistic system while focused on communication and interaction rather than correctness. For the child, the use of forms such as goed and foots is simply a means of trying to say what he or she means during a particular stage of development. Those embarrassed parents who insist that the child didn’t hear such things at home are implicitly recognizing that “imitation” is not the primary force in first language acquisition.