In the first stanza, the poet says 'sometimes in the midst of my play', which means he remembers his mother while he plays. The line 'a tune seems to hover over my playthings' shows he remembers the tune, but the opening line 'I cannot remember my mother' shows he does not remember the mother herself. The setting is indoor because the poet is playing with his playthings and recalling his mother rocking his cradle, which are indoor activities.