WIPS (Western Interior Paleontological Society) trip leader Jordan Sawdo was correct.  The fossil I found is indeed a shark's tooth.  I picked up the chunk of limestone because of the funny bumps on the other side.  When I turned it over I saw just a bit of white sticking out.  I thought I'd found a shell of some sort.  Jordan proclaimed shark's tooth.

I made some progress with Grampa Robinson's handed-down electric pencil and rotary grinder.  Even tried muriatic acid.  But after a while, I wasn't making any more progress.  Then I decided I'd spend my Maxtor award money on an airscribe and compressor.