cleaning up some fields in database

Hi!

I want to make some cleaning in my WP database because my wp_options table takes a size of 2mb!! (it’s almost bigger than post table!!)

I have many other blogs and never gets that huge size for wp_options…

After some analizing I see lots of entries like this:

rss_dd3c4c762f6c073e3c26497f53f083e6

and

rss_dd3c4c762f6c073e3c26497f53f083e6_ts

Someone can tell me what is this?? what sense makes some rss stuff in the wp_options table?? I can delete it? there are a lot of this stuff…

Thanks in advance!