is it safe to use a rubber stamp, that i got from a crafts store, on cookies?

Very good question and it is great that you checked. I am afraid that you cannot use those. There are food-safe stamps and I expect that someone will jump on here and help with a link to the source. If not, I know this question was addressed a little while ago in this forum if you do a search back. Again, it was great that you checked. Normal stamps and aluminum flashing to make cookie cutters are two of the biggest no-go's that I have seen occuring.

Okay, I hate not being able to help more, so I did a search and found this:

http://www.cakecentral.com/modules.php?name=Forums&file=viewtopic&t=665762&postdays=0&postorder=asc&highlight=stamp&&start=15

It has some good information and Bonniebakes talks about the food safe aspect. I do remember years ago that someone had a segment on a t.v. show using rubber stamps on cookies and it created a firestorm as they are not food safe. I think they people became more aware of the issues.

Edited to add another posting:

http://www.cakecentral.com/modules.php?name=Forums&file=viewtopic&t=663056&highlight=stamps

Oh, I just found a company that sells stamps that are expressly food safe for stamping on cookies:

http://www.sweetstampen.com/index.asp

Hope this helps!