Goal to become environment concept artist

[Tygerson]

I'd just go onto flickr.com and type in "HDR photography" or "HDR landscape." That will get you a bazillion images to start with. You can be more specific if you're looking for a particular kind of landscape. On flickr, you can sort by license such as "creative commons," which should be good to go if you're not selling the paintings.

Choose wisely--some HDR is gorgeous, and some is garish (think Thomas Kinkade on steroids).

I've found that amateur photographers enjoy seeing images based on their work, so it's nice to leave a comment like, "I loved this photo you took and painted it for practice. You can see it here [link]."

Wherever you post it your image, just put a link back to their photo. It's generally required in the creative commons license. Even if it's not required, it's a nice gesture to the person who got up at the crack of dawn to get you a gorgeous reference photo! :)