You don't say what kind of pines or how big they are. Southern pines are valuable when the market is good. Small job loggers would be interested in 30 mature southern pines.

If the trees are already down and cut up, you will have to let them dry for months before you can burn them in a brush heap.

INMHO southern pine makes good firewood if properly split and seasoned, especially if it is free. Trees that you have just cut need to season at least until next winter. Again, INMHO properly seasoned southern pine does not pop anymore than any other firewood, certainly not as much as red cedar or pecan. Creosote is not a problem with second growth pines if you keep your chimney properly clean. Creosote may be a problem if you are dealing with really mature southern pines that are largely lighter pine.