You can find quite a bit about Col. Shaver at the Arkansas History Commission. For a start, ask to see the Confederate General & Staff Officers File (on microfilm) for "Shaver". There will be a synopsis of his service record and there may be a few papers, orders, etc. related to him. There are also several other files related to Col. Shaver in possession of the AHC. There is even an oil painting of him in his later years on display in the administration offices.
A former pharmacy student of mine, Rob Shaver, is also a direct descendant of Col. Shaver. I take it you two are related?