Pottery Sherds?

[TGSQ45]

Hello,
I found these along the Missouri River today.... one looks to be check stamped and the other would be potentially simple stamped. Any thoughts on if these are pottery sherds would be greatly appreciated. Thanks!
-Tim

 

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[Older The Better]

First one not native, second one hard to tell could be a plain sherd

 

[TGSQ45]

OK, thanks for looking!

 

[CreekSide]

I don’t think any of them are pottery they look like roof tiles

 

[TGSQ45]

I don’t think any of them are pottery they look like roof tiles

Ok, thanks for your insights.