I know a lot about bottles but zip about marbles ..question

[RICKJJ59W]

When I dig bottles I find tons of marbles in privies to, I know some are pontil, and clay ect, but I have no idea what the names are or anything about them, I never realy looked into it because like I said bottles are my bag, but I have been checking you guys talk about the kinds of marbles there are, and its interesting, on ebay once I saw a marble go for 500 bucks! that's crazy !!talk about loosing your marble haha . here is just a hand full I found ,can some one tell me what kind they are thanks Rick

Ps: this site is the Bomb!

 

[bpk1]

The brown one to the top right, and the bottom two appear to be clay. Then again I'm new at this as well, so I'm not 100% sure.

Bren