I am embarrassed to have to ask. I know there is a feat or class feature or something that is like tatoos that help define your characters background but also grant certain abilities. I am being vague because I really do not remember much about it. I have searched and failed repeatedly to find it...any ideas would be welcomed. (I am hoping it is simply in one of the books I do not own, since I have rolled a 1 each time I search for it.) Thank you!

I believe you are thinking of the Dragon Marks - these are tattoo-like markings you gain or improve instead of taking feats and they grant various abilities. They were part of an Unearthed Arcana release for bringing the Eberron setting inro Fifth Edition. You can find information in the pdf here.

You can find the dragonmark feats in an Unearthed Arcana article for Eberron (it's old and never got updated, so take with a grain of salt): https://media.wizards.com/2015/downloads/dnd/UA_Eberron_v1.pdf

Thank you both. I knew I wasn't crazy and feel better since I was only searching this site...Yay thank you!

I do not know about other settings (and 5e) but this is how it was done in Planscape (at least computer version):

http://torment.wikia.com/wiki/Tattoos