Thanks for taking the time to sand those pieces. Definitely not oak or chestnut. Grain is very plain and uniform.
It might just be southern yellow pine: Southern yellow pine (SYP) consists of four major species: loblolly, slash, longleaf and shortleaf. ... This fast-growing species produces some of the strongest wood in North America. Structural uses, such as roof trusses and decking, are the more common uses for this wood.
Lets say it is yellow pine. Easy to google what is similar.
