Yogi Tea
Yogi's bag is non-heat-sealable abaca (manila hemp) and wood-pulp filter paper, closed with a knot rather than a heat-seal, with an organic cotton string and an FSC paper tag. The paper is oxygen-bleached (no chlorine, no dioxin), and Yogi states it has moved away from metal staples so the bag is fully home-compostable and plastic-free.
The outer envelope is the laggard: it historically contained plastic and the brand has been transitioning it to plastic-free stock, so current envelopes vary. The steeped bag itself is plant fiber and cotton.
How clear are their specs?
"Our Process" page confirms abaca/wood-pulp paper, oxygen bleaching, cotton string, no staple and no plastic in the bag - but the outer-envelope transition status is described only in general terms.