There are many options if you look at beyond the obvious, at least for some of these fields. Nowadays there are many self-publishing platform and different avenues for one to showcase your knowledge. A few possibilities:

- Agriculture, cooking ==> create article/video tutorials, search reddit forums for questions that people are asking, volunteer to write guest posts at blogs like MarksDailyApple

- Writing, fashion, art, travel ==> Start publishing and/or create lookbook. It seems that the founder of Glossier did just that and gained a following. Artists of the world, Patreon can be your resume.

- Photography ==> take some great photos, publish on Unsplash

- Sales, marketing, accounting, communication, research, writing ==> Quora, HackerNews, ProductHunt to engage the community + topic in your areas of expertise. Answer people's questions on reddit (the high-quality questions). How about start working on some projects at freelancing sites to sharpen skills, build portfolio, while gaining some income? Also, how about answering questions on Needgap? 😉