Cutting pen blanks from old parquet flooring blocks is very do-able. As the blocks usually have a thick coating of bitumen on the rear, getting that off can be a filthy business!
You can come across really unusual wood species too as much parquet flooring (hugely popular in the 1920s and 1930s) came from the colonies of the time, particularly East Africa. Many such species of timber are difficult or impossible to obtain now so you may have difficulty identifying what wood you have. Still, if it looks good, a rose by any other name...