A shelter can be greatly improved with some floor covering, matting and foliage from specific plants of a certain quality and property content makes ypur shelter more comfortable, helping to keep the warmth in and the damp and the insects out!

Strewn foliage

Any dry non toxic plant foliage can be strew across the floor of your shelter for dryness and comfort. Aromatic foliage serves the extra purposes of an repelling insects and smelling nice. When it has lost it's bounce and smell it can be replaced.

Trees; Conifers cedars, cypresses, firs, junipers, kauris, larches, pines, redwoods, spruces, yews - Coniferae/ Pinophyta; Brash
Found; most places ~ global.
Plant; Ferns - Pteridophyta; leaves (Caution Bracken which is common fern is reputed to have dangerous carcinogenic spores)
Found; everywhere ~ most places ~ global.
Plant; Rosemary - Rosmarinus officinalis; arial parts.
Found; scrubland, waysides, hedgerows, rocky slopes ~ coastlines ~ mediterranean Eurasia. Medicinal.
Plant; Thyme - Thymus; arial parts
Found; heath land, open spaces, rocky places, scrubland, waysides, wasteland ~ Africa, Eurasia .Medicinal.
Plant; Mint Mentha sp; arial parts
Found; waysides, moist woodlands ~ North America, Asia, Australia, Europe. Medicinal.

Matting

Plants with long air filled stems make good matting. Much like thatching, they are bundled and bound together.

Plant; Grasses - Poaceae; open spaces
Found; global.
Plant; Reeds - Phragmites; root; arial parts
Found; in and by fresh water, wetlands ~ temperate and tropical regions ~ northern hemisphere, Africa, Australia, Eurasia.
Plant; Rushes - Juncus; ariel parts
Found; in and by fresh water, wetlands ~ globally.
Plant; Sedges - Cyperaceae; aerial parts
Found; by water, wetlands, marshes ~ temperate to tropical areas.