Bike buying

My mom just now said next week with her tax refund shes buying us bikes,what kidn should I get between a Mongoose or a Mountain Bike.

Mountain bike, though I would suggest something different, other than those two. Raleigh's are SUPER nice. I saved up and bought one a year or two ago.

mongoose they have pegs

I think mate mountine bike

it is better then a stpid bmx you can go bike riding through grass,mud and anything that comes into your way

so there MOUNTINE BIKE

Mongoose is a bike company that makes several types of bicycles for all different disciplines.
bmx, mountain, road, touring etc.
every bike company makes a different range of products varying in quality and price.
So depends what you intend to do with your bike and how much you want to spend.
for just biking around you don't need anything fancy or expensive.
gears or single speed upto you.
brakes however are necessary.
helmet is a must
try a few out if you can, stay away from big box stores Walmart especially.
terrible service after the purchase and poor quality products.
too cheap won't last and too expensive could be overkill.
also remember to buy a lock, if the bike is say worth 200 or more, it is worth the 20 or 30 bucks to keep it.