Turnip question... Help!?

[Livv]

So, I have been playing animal crossing new leaf for quite a while now, and i have heard people sell turnips for a ton of bells!!! I dont even know what they are or where you get them from! (Ive heard of the stalk market, not sure what it is though! ) Can someone just tell me:
What are they?
Where do you get them from?

PS: I know that there are different selling prices at re-tail... etc! Help please!!!

From Livv!!!

 

[talisheo]

Turnips are the equivalent of stalks. You can buy them on Sunday mornings from 7am till 11:59am from a character named Jonah. Her prices vary from 90 to 110 bells per turnip.
Everyday at Re-tail prices change, so you have to ask everyday to see what prices turnips are being bought. But you can find high prices on this form pretty easily.
If you do not sell your turnips by a week they will expire and you will lose all of your money D :

 

[darkfire25]

On Sundays, a boar named Joan will wander around your town from 6 a.m. to noon. You buy the turnips from her. Then you sell the turnips at Re-Tail. The prices change. Every day, there is one price before noon, and one after. Of course, there are no prices on Sundays because you can't sell on Sundays.

 

[........]

The trick is to buy low and sell high. So buy a bunch of turnips when the prices are around 100 bells, and sell at 300+ bells to make a big profit.

 

[Livv]

thanks everyone for the suggestions!!