How much Are these Magic (Magic the gathering) cards worth?

It depends. all the of rating are only if it is in Near-Mint or Mint condition.

Vexing Shusher

If the area where it shows the text says "Shadowmoor" in the background or something like that, people are gonna charge a lot for it, around $8, but you won't be able to sell it for a decent price (as in $4+) unless you wanna wait a bunch of years, as it's not a really old edition.

If the area where it shows the text does not have a "dramatic" background, it's only worth around $1, and you'll probably won;t be able to sell it for a higher price.

Knight of new alara

Give it around $2

Sorry to reveal the low prices, but they're not old editions.

Have fun!

The two foil cards that you have are the release promos (you can tell because they will have a date stamped on them). They're only worth a couple of dollars each.