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.
A cover letter may be required as part of the job application process. If it's optional, I recommend including a cover letter because it's the best way to pitch your case for an interview. Here's how to write a cover letter and what to include in your cover letter, plus cover letter examples and templates.