These are generally known as "charity rags".
The textiles picked up from shops should be donated
from UK sources, not from imported clothing brought
into UK by the charity, nor from landfill sites or
rummage sales.
These should be lots of mixed UK donated clothing:
household textiles and wearable paired shoes left over
after retail sales from the charity shops.
All should be clean and dry, and should exclude pillows,
duvets, carpets, balls and cones of wool, off-cuts
from manufacturing process and unfinished garments,
hard toys, books and bric-a-brac, coat hangers, sharp
objects and single (odd) shoes.
The mix should reflect all the categories sold e.g.
shirts, dresses, jackets etc. The usual composition
should not be changed due to bulk sales of particular
items (e.g. cotton clothing sold as cleaning rags)
unless specifically agreed with the merchant.
Packing: water-resistant sacks (e.g.
polythene) at a weight convenient for shop handling,
storage and collection, usually 8 to 10 kg unless specifically
agreed that an alternative packing method is more suitable
e.g. hessian sacks for shoes.
Used textiles, shoes and handbags should all be packed
separately.