You can search online for little spells, but for reference About.com is fun. Patty offers some rituals and many beautiful articles.
How about making an offering of little breads and cakes and planting them around your area as a show of thanks? Something that would be healthy for animals and humans alike to eat. Because Nature and the Gods are so closely intertwined, an offering that helps and supports Nature is always a good idea, and it also helps in opening up communication to the Animal world. However, that is largely my way. When I am showing thanks to someone, or show my love, I make them food. That's just the way that I am. How do you show the ones you love that you care, or give them thanks? Can this be adapted in a meaningful way to show your appreciation and love for your deities?
Edit to add: Here
is an interesting ritual. Note of caution: She says to annoint with the blessing oil. Oils can burn, are rarely meant to be used on the skin in such a strong mix, and never should be placed on the eyes. You can opt out of the eyes part, do it symbolically (i.e. annoint your eyes on the higher levels of your body, a few inches away from your eyes), or use a tea or water you have blessed/consecrated instead.
This is more of a dedication ritual than a thanking ritual, but this can be adjusted to fit your needs.