I'm afraid coin grading isn't that simple. For starters, you have to send your coin to a Third-Party grading service such as PCGS, NGC, ANACS, or ICG. PCGS and NGC charge membership fees on top of submission fees and are generally considered top tier grading services by collectors. Moreover, you should probably post photos of the coin you'd like to have graded. Our members are more than willing to offer you their opinions and expertise and possibly save you some money.
If you're talking about someone who can grade a coin for you, you can post clear pictures here and get several opinions (even professional ones) to assist with that. If you are looking for a recognized third-party certification service which will grade and encapsulate (slab) a coin for you, then I do not think there is one in Minnesota. PCGS is in California. NGC is in Florida. I do not recall offhand where ANACS and ICG are, but I'm pretty sure they are not in Minnesota. There are no other American third-party certification services with any noteworthy level of recognition and reputation in the marketplace. Edit- @Bradley Trotter pretty much echoed my advice above, but was a faster typist than I.
Many knowledgeable members here that will give you an honest grading opinion if you post good photos.
If I recall correctly, @lordmarcovan, I believe that ICG is located in Tampa, Florida, and ANACS is still located in Englewood, Colorado. ICG used to frequent the Greater Jacksonville Coin Club Coin Show, although the last few times I went, they weren't there.
It is clear from your question that you aren't familiar with the coin collecting hobby and its terminology. So, in order for us to help you, it would be most beneficial if you would tell what your goal is in needing a "grader". I say this because all of us are coin graders but we don't all serve the same functions within the worlds of the hobby and the hobby business. So don't make us do all the work by guessing what you want, tell us.
If you just want regular American coins graded, I highly recommend ICG. I have collected for years and bought many coins in PCGS, NGC, ANACS and ICG slabs, but I decided I wanted my low end SLQ (Standing Liberty Quarters) set slabbed (because some of the coins I bought for it were in slabs already). So I sent a batch off to ICG on their economy special (CoinTalk members can submit for $10 per coin, I think with a 10 coin minimum, you have to mention your affiliation on the submission form). You don't have to join an organization first, like PCGS or NGC, you just download the .pdf form, print it, fill it in and ship it off to them, I got them back in a little more than 2 weeks. Shipping costs extra and if you want coins "conserved" (cleaned without damaging) that's an extra $5 per coin. If it's a super expensive coin and you want to maximize resale value the market definitely prefers PCGS slabs. I only speak from my own experience, others may have different views.