sew / sow
To stitch versus to plant.
To sew is to stitch: sew the hem. The past is sewed; the past participle is sewed or sewn. To sow is to plant seed: sow the field. The past is sowed; the past participle is sowed or sown. Do not write sow a button.
Examples
Use She sewed the tear.
Use They sowed the lot.
Avoid They sewed the lot.