Mrs. Caldwell was a near-victim of the Carrigans.
Mrs. Caldwell purchased a wreath made out of Meadowsweet for the fireplace. This unknowingly attracted the attention of Edward and Madge Carrigan, who were planning on taking anyone with these wreaths as sacrifices.
While sleeping in bed one night, a large creature entered Mrs. Caldwell's bedroom and attacked her and her husband. The creature attempted to kidnap them but Mrs. Caldwell began screaming. She was instead knocked out while her husband was stuffed in a bag and dragged away, their son witnessing most of the incident.
Sam and Dean Winchester came to the Caldwell family home and spoke to Mrs. Caldwell, who now sported a black eye. She could tell them little about the attacker, but Sam noticed the familiar looking Meadowsweet, and asked where she got it. Sam explained to Dean later on that previous victims also bought this particular wreath.