More Subject/Verb Agreement Confusion

A recent request in the local "Good Neighbors" column here in Birmingham contained a sentence that read as follows:



M. R. wanted to buy one of the pink and white commemorative plates that was given to adults who were in attendance when South Avondale Baptist Church held its last service.



At first glance, this sentence might appear to be correct. The verb "was" is singular, and the word "one" is singular, so they agree. BUT, read it again. M. R. only wants to buy ONE plate; however, many more than ONE were given out on the day of the last church service.



In this case, the clause "that WERE given to adults who...." describes PLATES (more than one) not the ONE plate M. R. wanted to buy.



The sentence should read as follows:



M. R. wanted to buy one of the pink and white plates that were given to adults when South Avondale Baptist Church held its last service.