Horseradish is at its best in fall and winter. Like so many other root vegetables, however, it stores well and is often available in decent shape well into spring. Jerusalem artichokes/sunchokes are brown nubs, that look a bit like small pieces of fresh ginger.
Using Ms. or Mrs. in a cover letter depends on whether or not you know the marital status of the woman. If you are ever uncertain, it is always safe to use Ms. because it does not make an assumption about her marital status.
You should never use the same cover letter for different job applications. Your cover letter needs to show that you know what the job involves and what the organisation is looking for. To do this you need to be as specific as you can about your skills and qualities and how they match the job or organisation's needs.