There is no relationship between Come and Wheat in English. But there is a close relationship between Chinese character 来 (Come) and 麦 (Wheat).
Let's take a look.
The shell bone script for Come is
which did mean Wheat originally. We can see that it looks like a plant of wheat.
It is a pictography character.
Its big seal script is
The shell bone script for Wheat is
Let's see its big seal script first, which is easier to be understood.
We see the top is 来,which was wheat. The bottom part means "Foot". The character means someone who hold wheat and walking here, which was used as Come.
It is an ideogram character.
However, the two characters exchanged the meaning in long history.
來,original meant Wheat, but it means Come
麥,original meant Come, but it means Wheat.
I don't know why this could have happened.
The small seal script for Come is
and the small seal script for Wheat is
The clerical script for Come is
The clerical script for wheat is
The current standard printing script for traditional character of Come is
來
very similar to the clerical script.
The current standard printing script for simplified character of Come is
来
changed a little bit in the middle, but still similar to its clerical script.
The current standard printing script for traditional character of Wheat is
麥
very similar to clerical script.
The current standard printing script for simplified character of Wheat is
麦
not much similarity left on the top part.
The pinyin for 來 (Come) is Lai2.
The pinyin for 麥 (Wheat) is Mai4.