Second pic is the mule. I wouldn't be surprised if it's lying down because it hurts the poor thing to stand! Its feet(hinds at least) are in a REALLY bad way. Donkey's left fore at least is also terrible. Can tell very little from these pics tho. Ditto to others that you need to get a good equine vet involved as well as a farrier, urgently. They are suffering. This is a prob that horses/donks are still commonly put down for.
How long have you had them? How much do you know about management & feeding of donkeys properly generally? How about training? I'm not at all knocking you for not knowing better, but assuming from this thread you don't know much at all(?).
You can learn a fair bit here, but esp considering the steep and urgent 'learning curve' I'd suggest some serious study, and hands on instruction, if at all possible, starting immediately, if you haven't been already. It's a big commitment to take on 4 equines & keep them well, let alone being totally new to them, let alone that they are in a very bad, long neglected way & need intensive care before you started...
Along with needing a good farrier... Many many months ago, you need to get them off any rich grass or feed immediately. Donkeys/mules suffer way more from IR/obesity than horses even. You need to do research on how to manage & feed them well & also on laminitis/founder, as the 2 pictured are both founder cases.
I would highly recommend you also get onto ECIRhorse.com and also get the book 'The Pony That Did Not Die' by Andrew Bowe - a great resource about laminitis rehab. I will PM you with more suggestions.
Unfortunately I'm not surprised the 'rescue' let these guys remain in & go to you in such a state - Unfortunately people who start 'rescues' are commonly bleeding hearts without much clue or sense of reality themself, so they 'rescue' animals & then continue to neglect or otherwise let them suffer, then let them be taken by just anyone.
Yes, I would believe how hard it is to find a farrier. Especially as you have donkeys, especially if they aren't well trained(& even if they are, I'm betting these guys would be difficult for hoof handling due to pain). Especially as they have come from a 'rescue' and have been chronically neglected with deformed feet. It's a hard, dangerous job anyway, and donkeys think/act ...kick differently to horses, and are renowned for being kept as pets and not being trained.
If you have stocks, so a farrier can do the job safely regardless, that would help. Then you can also line the area with thick closed cell foam or such, for the donks comfort and rig up a sling, so they don't need to put more weight on one foot while lifting another.