Which address was your packet sent? Did you get the tracking number from your lawyer? If yes, did you a see a delivery exception and then eventually was the packet picked up?
If yes, then at least you can be sure that they received your package. If the checks were correctly made (right amount and split between you and your spouse/dependents), I don't see any reason it won't eventually get cashed. Read this to understand what goes on after they get the package:
http://uscis.gov/graphics/fieldoffices/scnational/index.htm#E
How We Process Your Application at a Service Center:
Normal Processing:
The first step is the receipt of mail. Mail is generally opened within twenty-four hours of receipt. The majority of mail arrives on Monday (40%) and Friday (20%). The other three days of the week share an equal amount of mail. Because of the volume of mail arriving on the two busiest days, sending a case via express mail to arrive on either of those days does not ensure faster processing. The lower volumes of mail arriving on Tuesdays means that the mail is usually opened by Tuesday evening.
Applications are stamped with the time and date of physical receipt, not the time and date they are actually opened. Mail with fees enclosed is routed immediately to mail assembly. Cases that are filed prematurely (before the applicant was eligible or met the legal criteria) or that were filed on an outdated form are prepared for manual rejection at this point. Cases lacking proper signature or correct fee are identified for system rejection.
Mail without a fee enclosed is considered correspondence and is sorted by type, if the appropriate destination can be quickly determined. If mailroom personnel are unsure as to the routing, the material is sent to the Customer Contact Services unit where it is read and either responded to or routed to the appropriate division for action.
Properly filed cases and cases flagged for system rejections are then forwarded to the Data Entry unit. In the Data Entry unit, information is keyed into the USCIS computer system and fees processed.
The Data Entry unit collects the appropriate fee or when necessary, rejects the case if the fee is incorrect or the form is not signed. If a case is not clearly acceptable, it is immediately passed to our Case Resolution unit for review. If they are unable to overcome the obstacle to processing, the case is returned to the applicant/petitioner for correction. Receipt or rejection notices are generated during Data Entry and mailed no later than the next morning.
Fee receipts are printed and mailed after the electronic record is created. This means the date on the fee receipt may be different from the date the mail was received for priority date purposes.
Once the fee has been properly receipted and the electronic records created, cases are routed to the Work Distribution unit to await a call for work by the Product Line or Field Office.
If the application will be adjudicated at the Service Center, an Adjudications Officer will review the case; the appropriate data (including cable requests) will be noted on a processing sheet and forwarded with the application/petition to the clerical section. The system is then updated, and the completed application or petition is sent to the file room, consulate or other appropriate office, and original documents are returned as required.
The Center makes every effort to process each application/petition without returning it for further information. Applications that are well prepared take less time to process, thereby facilitating faster processing of all cases. Therefore, to help applicants better prepare cases and applications before sending them to us, please refer to our General Tips on Assembling Applications for Mailing. Following these procedures will help us to serve applicants better and faster.