[JCamp]

The first pictures look like maple to me. Probably some version of water damage causing the darker areas. The last pictures look like pine to me. Can’t be 100% sure but if I found them along the road that’s what I’d think they were. It would help to know where the pallets where made. My guesses are base on Ohio lumbers and guitar woods. There are thousands of different trees in the world and we all like to make lumber from them so if it was built over seas it could be anything.
careful with the finish on them. Some of the stuff is unhealthy to breath....well about all of it is

 

[FoxxJump]

I do believe that the one you are talking about is pine, I didnt realize it until after I ran it through the planer. I am not sure where they were made but what made me take a closer look at them is that the pallets were made to carry extremely heavy concrete forms and I figured they would use some kind of hardwood to support them. My guess is one of the boards was replaced at one point with a pine one as that is the only one I see of them with the end grain so far spaced apart. I also think that they grey could be water damage like you said (or spalting) but I am not sure. I am not able to read the markings on the pallets so I have been using a mask to be on the safe side and just set up a dust collection rig on the planer to help minimize the dust flying in the air. I also have it set up outside as well. Thank you for the input

 

[FoxxJump]

Those latest pictures just look like blue stain pine to me. The bark looks like pine to me too. Looking back at the finished boards, those may also be pine.

The one board you are talking about I am pretty sure is pine as well. However then end grain on the rest look completely different. I think A board was replaced at one point on the pallet I dismantled. Sorry I didn't catch it before posting pictures of it. Its hard enough to figure out one type of wood.

 

[FoxxJump]

Thank you to everyone who has stuck around so far, I got a closer look and the end grains on the wood and compared it to the one piece that I am assuming is pine, also in the picture I have it compared to a piece that is know to be pine (unless the big box store lied) and also compared to the wood that show some pores in the end grain. Thanks for looking. Even if I never find out what this is it has definitely been a good learning experience!