~ものだ (nostalgic past)

When I was a boy, I used to lie on the grass and gaze at the white clouds.

When I was a boy, I used to lie on my back on the grass and gaze at the white clouds.

I used to often read detective novels before bed.

I used to read any novel I could get my hands on.

She used to wash her hair before going to school.

She used to visit me regularly.