can I have civil marriage in MD if i'm not an US resident?

You probably qualify. Here is a link to the MD Stae court site which describes procedures for obtaining a marriage license. Assuming you meet the criteria as decribed in the licensing process, you should have no problem in obtaining a license and with going through a civil ceremony memorializing your marriage. http://www.courts.state.md.us/clerks/queenannes/marriage.html