I looked on google maps and there is a St. Matthews Cemetery off county hwy P, which is actually listed as being in Ontario, WI.
That is the only one that comes up when I enter Wellington Twp., with or without St. Matthews and Lutheran cemetery.
It is kind of strange it comes up as Ontario, when it is north east of there, and south east of Wilton Twp. If you look on the map, nearby roads are: Nordale Ave. and County Z, which turns into County P but then P splits off and goes south.
Sorry, I don't know WI at all, so if you live there you can probably give better directions. There is another cemetery nearby called Calvin Day Cemetery and is SW of the St. Matthews one.
Hope this helps.