My 7 month old grandson has "thumb tack" size (diameter) bump/lesion on the side of his scalp. not compressible. not seemingly painful. any ideas ?

Many possibilities: If brown, probably a birthmark. If red, probably an angioma (also a birthmark). If flesh-colored, probably a mole, or any of several benign skin tumors. There is really no way to narrow it down further than that without physically looking at it, so have your doctor or a dermatologist take a look.

Plenty of answers bu: But you should encourage the parents to have him seen by the pediatrician and if needed by a dermatologist to allay fears of anything harmful.