It looks like it could be elm.
Hi Bill.
I think it might be elm.
Interlocking grain is a hallmark of elm.
Green stripes are commonly found it it as well.
http://www.wood-database.com/lumber-identification/hardwoods/american-elm/
http://www.wood-database.com/lumber-identification/hardwoods/wych-elm/
I don’t know where in the World you are live, but the above links covers American elm and Wych elm (which is common in Europe).
Brgds
Jonas