I'm VERY pregnant,not able to do much, and therefore,bored so I'm loving these type of mamasource questions right now. :)
When I was pregnant with a boy, I liked the name Gavin and then my Dad ruined it for me when he told me it sounded like a "skinhead" name. Then we watched that horrible American History X movie with Edward Norton and lo and behold, one of the guys on there was a Gavin! Ugh, I hate when certain things ruin perfectly good names for you. Gage has been ruined for me as well. And Harley...it was my dog's name when I was 9. :/
I like Jackson and Mason on your list. Cash is a little on the "trendy" side therefore I'd use it as a middle. ie: Jackson Cash. With Jackson and Mason, these are my favorite combos:
They have nice a ring. At a playgroup a couple of mos ago,we met little boy twins with the names Jed and Jagger. I thought that was cute.
It also depends what your other children's names are. It's nice when they all kind of match a little.
And lastly, if your last name is really long, I'd go with the shorter first name,Mason. If your last name is short,then Jackson. I like Jackson Tyler too as per a mom's suggestion below but not as much as Jackson James.
Funny how names work though. I had my childrens' names all picked out a month into my pregnancies and then when I started bonding(usually when movement begins and discover the sex), the names just didn't fit and I changed them to something completely different and unexpected about a week before the due date. Now, I can't imagine their names being anything else. Of course, my daughter isn't born yet,but she is due any day now!!
Congrats and happy naming! Let us know what you decide. :)