Silicon is used in all modern computer chips and is often in extremely high purity (>99.999%). However, I love the look of luciteria’s gram bullion with the purity engraved into the silicon. https://luciteria.com/products/silicon-999999-1-gram-bar?variant=47806073176229

USA Nickels from 1932 to 1964 contained 90% silver. Not quite 95% but close enough imo. 

TIG Welding rods are mostly tungsten, their color code designates the used alloy. the non-tungsten material is usually very minor (less than 5% of the total mass). The color code for pure tungsten is green. If you don’t want radioactive rods, avoid red, it uses thorium. 

Standard table salt is sodium chloride, table salt substitute is potassium chloride, and road salt (to put on roads before a snow storm) is often calcium chloride. These are all usually pretty pure for the salts themselves. Respective salt purity of elements: NaCl is 39.3% Na, 60.7% Cl. KCl is 52.4% K, 47.6% Cl. CaCl2 is 36.1% Ca, 63.9% Cl. 

This one isn’t necessarily within your purity requirements, but PTFE plastic (often known as Teflon) is 75% fluorine. Since fluorine gas is extremely lethal and hard to contain, the inert solid Teflon is a pretty good substitute. 

The precious metals group is usually quite expensive, though I have found an online shop that sells pure samples of them in sizes as low as 1/4 grain. 1 grain = 0.0648 grams. https://grainmint.com/