just an fyi - if you have access, Wondertime magazine had a great pull-out (it was an advertisement on one side) of different leaves in autumn colors. They are not real photographs, but I think they are very good for preschool/kindergarten age IMO. I saved it to look at later with DS.
i love all the dltk websites. i also love <a href="http://www.makingfriends.com" target="_blank">www.makingfriends.com</a> they have lots of free stuff, or you can purchase things super cheap ....but be sure to put an "s" on the web address...or you will "make a friend"<img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/lol.gif" style="border:0px solid;" title="lol"> . i also LOVE my oriental trading magazine. and my favorite book is "a year of crafts for kids" by kathy ross. it covers all of the holidays & seasons. someone posted a great website for the holiday calander year a couple of days ago. maybe they will repost it here. i'd use that link for holiday/seasonal ideas, then come up with a great craft to go along with it, and you can also google a lesson plan about it to make it extra fun and educational!
The library is a nice resource for this stuff, and there are tons of seasonal themed webpages for kids. You can find nice printables too! I am Pagan so the seasons are celebratory by default, and I have often found some neat word searches for Dd or coloring sheets, craft ideas, and recipes. <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/smile.gif" style="border:0px solid;" title="smile">