mind, mined

Mind or mind means mental faculties, intellect, understanding, or will--
Make up your mind!
He has a good mind, but he never does any school work.

Mind is also used as a verb ( action word ), meaning to object to something--
He won't mind if we have to walk home.
They won't mind if we are late.

Mind is also an old-fashioned way of saying to watch over--
Will you mind the store while we go out for lunch?
Mind the stove; I have to answer the phone.

Mind is also an old-fashioned term for obey, or pay attention to--
Tell the children to mind the sitter.
Mind your manners!

Mined or mined ( rhymes with mind ), is the past tense of "mine", meaning to dig up out of the earth, or to dig out of something, literally or figuratively--
They mined coal here in the 1920's.
They mined for silver in Colorado.
They mined the stacks of the library, looking for interesting old books.

Mined may also be the past tense ( yesterday, or some time ago  ) of "mine", meaning to hide bombs or explosives underground or underwater--
The harbor is mined; we won't be able to get out.
The field is mined; we can't cross it.

Now that you know that, you can say--
"He may be out of his mind, but he claims that he mined for gold right here in town."

Note--"mind" may be a noun ( thing or idea ), with a singular or a plural form--
He won't make up his mind.
He is of two minds on the subject.
"Mind" may also be a verb ( action word )--
I mind the store, you mind the store, he minds the store, we are all minding the store.
Yesterday we minded the store.
Tomorrow we will mind the store.
Note # 2--"mine" may be a noun ( thing or idea )--
"In a canyon, in a cavern, excavating for am mine..."
"Mine" may also be a verb ( action word )--
I mine for gold, you mine for gold, he mines for gold, we are all mining for gold.
Yesterday we mined for gold. Tomorrow we will mine for gold again.
Not to be confused with "mine", a possessive  pronoun meaning belonging to me--
Hey! That sandwich is mine!
That is yours, this is mine.
Here are yours, mine, and ours.