Please help, my dog is vomiting a LOT?

I have a 10-11 month old Jack Russell/ Basenji mix, whom I adopted about a month ago. She is spayed and approx 22 pounds. I took to the lake today, which I've done a few times before, to play with one of her best doggie-friends. She ran and sniffed around and played like normal, but when we got home, about 3 hours later she started throwing up. The first round of vomit was undigested food from that MORNING, and all subsequent regurgitations appear to consist of random things she ate at the lake. I have no idea how she managed to eat so much random sh!t (trust me, it's a LOT), because I was watching her most of the time and she appeared to just be sniffing/ playing. However she's now vomiting up rocks, sand, grass, dirt, little pieces of plastic, etc etc etc about every 30-45 minutes. I've taken food away and given her access to fresh water and am keeping both eyes on her. She appears a little lethargic, but that could just be because it's 3:05 AM here and she was running around all day.I'll be taking her to the vet first thing in the morning, but do you guys have any suggestions until then? What might have caused her to vomit undigested food? Why she ate 1-2 cups of rocks, when she was seemingly having fun and had no reason to be bored? Is this severe enough that I should take her in to the emergency clinic right away?

If she is just eating random things, she could have picked up most anything. Poison would be my first concern. A lot of people put out poisoning around water to keep the rodent population down. I think you might have been concerned when your dog started eating rocks. They don't digest well and she can have something that she can't get out or eaten something that perforated her intestines. I think this is bs. Is this serious enough to take her to the vet...no just let her die.

I'd get her to an emergency vet. If she's brought up stones, she may have one or more that are causing her to block up the other end. She'll need x-rays for starters. Continual vomiting needs to be stopped (dehydration) too, but if she's produced all this junk, the blockage aspect would have be running to a vet. I'm not one to hit a vet for everything either.