I'm planning on starting a new site which has the word "happy" in it, for the logo I'm planning to use a smiley Would it be illegal if I got some smileys from those smiley sites and used it in my logo? If I did use it, would I have to mention that the smiley used in the logo is owned by blah blah?

The smileys I'm talking about are those big smileys, size of an avatar, not these kinds of smileys:



I can't really find any smiley stock free images they are all paid, around $3 just for one picture..