If all you are wanting is a macro function, and not so much for portraits, then the FD 50/3.5 will work on your camera with an FD/EOS adapeter. Make sure you get the adapter that does not have any correction glass so it functions as basically a very small extension tube. Using a manual focus lens like this means you have no auto focus (which you dont need for macro anyway) and of course the view finder will darken as you stop the lens down. You will also have to shoot in aperture priority or manual mode. But it works, I used to do in on my old 40D all the time until I got my NEX 7 which is so much better for using old glass.
If you are considering older lenses for macro (which I heartily recommend) you might look at something in the Contax/Yashica mount or the M42 mount. You can get a simple C/Y or M42 adapter for your EOS that has no correction glass and is basically just a spacer. These lenses, unlike the FD, can be used for normal and macro photography throughout their entire range. So regular picture, portraits and macro are all doable.
If you go with C/Y then you open up the option of some really nice Yashica ML macro lenses along with the Zeiss Makro Planars that came in 60 and 100mm focal lengths. Those lenses are beyond reproach and capable of great photographs. The Zeiss lenses are pricey but the Yashica ML macro lenses (55/2.8 verion and 55/4 version) can be had for much less money with very similar optical performance. They were after all made on the same assembly line at the same factory. (With the small exception of some lenses that were actually made in Germany by Zeiss).
M42 screwmount will open up TONS of options, but there are more dogs floating around in this mount. If you stay with the bigger players (Pentax SMC, Fujinon EBC, Yashica Yashinon) you cant really go to far wrong.
One other mention in old manual focus glass should be the legendary Tamron SP 90/2.5 in adaptall mount. The neat thing about this lens is you can use it right on your EOS if you can find the somewhat rare Adaptall/EOS adapter. If you cant, you can always use the readily available Adaptall/CY mount and then put it on your CY/EOS adapter.
Examples of several of the lenses mentioned here can be found in my macro set on flickr. Shot mostly on the NEX 7 but many on my old 40D.
http://www.flickr.com/photos/8539414@N07/sets/72157626866276690/
One other mention. Most of these require an extension tube (usually around 27mm) to reach a 1:1 ration. Most only go to 1:2 natively.