Dear Ms. Smith,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located a series titled Case Files for Warrants Issued under the Act of March 3, 1855. For access to and/or copies of the files for James & Charles Jarvis, please contact the National Archives at Washington, DC (RDT1) via email at firstname.lastname@example.org. We aso located a series titled Abstracts of Military Warrants for the Act of 1855 and include Iowa. The abstracts are in the custody of the National Archives at Kansas City (RM-KC). Please contact RM-KC via email at email@example.com for more information.
In addition, the Bureau of Land Management General Land Office has digital copies of the patents for both James Jarvis and Charles Jarvis at https://glorecords.blm.gov/results/default.aspx?searchCriteria=type=patent%7Cst=IA%7Ccty=%7Cln=Jarvis%7Cfn=James%7Csp=true%7Csw=true%7Csadv=false.
We hope this information is helpful. Best of luck with your research!