I have an apple tree that makes little green apples, they turn a little red but when you bite into them, they are very sour.  Any ideas?  Can I cook them down with sugar and make pies or cobblers?  Never had this kind of apples before.

Patti is it a crabtree ???   Ball Blue has a Cranapple butter .

Boil them down for juice.  Then use them for blackberry-apple jelly or get some red zinger tea bags and make red zinger jelly (heaven on a biscuit).

Also make red pepper jelly and leave out the red food color.  Or candy them and serve them as a side dish or a garnish on cakes.