(Sorry to intrude… this is Kay, following up on your wool question). Linen may work, but is probably going to be more expensive than wool, and will drape more roundly than wool does. Muslin is way too light for a cloak. Look at the softly spun polyester suitings and similar for cheap. Actually, I can often get decent wool flannel and the like for $5-8/yard.)

As to your raised beds… how long do they need to last? In a cool climate, plain ol’ 5/4 cedar will last at least 5 years, more likely 10; untreated 2×4 will usually last at least 4-5. Cement block is good for permanent, and you can also just build up the bed with sloped sides — essentially a long mound — and simply repair it a bit in the spring by shoveling the washout back to the middle. This is also a much easier construction technique for incorporating compost and similar materials into later.