Here are some local and state resources you could try:
For marriages up to 1900 check out:http://www.cyberdriveillinois.com/cgi-bin/archives/marriage....
For deaths 1916 to 1950 check out:http://www.cyberdriveillinois.com/departments/archives/genea...
The Rockford Public Library has a great local history research room. All directories back to before 1850 would be there. They also have all the Rockford newspapers (obits) on microfilm back at least as long (1850). Perhaps they would copy info and send or you could make the triip. I have heard that the gentleman that mans the local history room will do some basic research like this for a small fee.
The Winnebago County Clerks office keeps all the birth/marriage/death records on microfilm. If you have good dates they will make copies. Cost is $7-15 each search depending on how good your dates are. Be sure to state that you are doing genealogical research and give your relationship to the person(s). They have much cross reference printouts available (free) in a section of their office on births/marriages(by male and by female) and deaths.
IF BURIED LOCALLY
Many larger local cemeteries have good records. Smaller ones may have listings in the Rockford Public Library local history room. (nice facility).