Bramble: offer up the brown bags on freecycle? I would take them from you if I lived close enough! for re-use. We get our cards in brown bags but these aren't large enough nor strong enough to reuse for much else. So onto our compost they go.
Those bags that have turned into confetti are biodegradable ;-) - doing what they were designed to do! I had some do exactly that, I bought some, put them under the stairs because I didn't want to use them up

; forgot them for 5 years

and found, yep, confetti - what a waste

except they went into our compost.