Linens, which refers either to household tablecloths and napery or to ecclesiastical altar coverings and the like, and in either case references things made of linen fabric.
Nickels, by the way, are no longer made of that metal.
A small forest is a wood or woods.
There are areas where a small lake or large pond is referred to as a water, particularly as a part of its proper name.
It’s been my experience that in the indefinite or plural one refers to one or more bars of soap, but in the definite it’s most common to reference it as “the soap.”
A marker, as of a grave, a boundary, or other desiredly-durable nature, which is made of granite, marble, sandstone, etc., is nearly always referenced as a stone. This is distinct from the usage where a large pebble or small cobble is also a stone.
The garb worn by jockeys in horseraces to enable easy distinction between them is their silks.
Very obsolescent now, but still clear enough to anyone encountering the word, is the description of greaves, vambraces, chaps, etc., made of leather and worn for protective purposes, as leathers.
There’s a near-miss worth preserving. In the days before photocopiers, xerographic copiers, and the like, the means of making a second or additional copy of that which you were typing, on a typewriter, was to create a sandwich where the top and bottom were plain blank white paper and what lay between them, face down, was a sheet of thin paper which had been coated with a dried suspension of fine carbon dust, called “carbon paper.” When this complex was inserted into a typewriter’s platen and you proceeded to type on the top sheet, the impact of the keys would dislodge carbon dust in the shape of the letter typed from the carbon paper and lodge it on the blank bottom sheet, which was in consequence called a carbon, or carbon copy.
Another near miss is the use of tin to describe a metal can usually used for food storage, either by having an airtight lid or by being a sealed canister containing canned food. In this case, the can is made of iron, but the reference is to the tin coating that covers the entire exterior and interior surface to prevent oxidation.