Linen, see the blue flax fields throughout the UK with it's flowers, the flax seed (linseed) has outstanding health benefits.  

https://www.health.com/nutrition/flaxseed-benefits

 But the plant is also used to make linen which is a very versatile thread and fabric, it's anti bacterial, odour-resistant, very long lasting. 

It also takes colour very well and becomes softer with age.