Sounds awesome! Farmer R was dropping off some lovely fresh green hay for the pasture critters and we got to talking, and we got around to the topic of straw, (need another four large square bales dropped off) and that lead to asking about if he had anything in a tighter round bale for the straw that would work as a target practise bale for the crossbow and for my bow that I want to be able to shoot off the horse by the end of the summer!
Trust me on this, with hay supplies as tight as they are right now, no way! would I ever consider doing this with a hay bale, even if I paid for it, it would just be wrong this year to do that to a good bale, when I know that so many others are doing without.
But I was thrilled when he said, yes, he had a bad bale that would do just what I wanted and then I was even more pleased when he said, do you want them all, and I said, how many, and he said, six or seven or so.. I snapped them all up, they are a mix of weed/old hay off the edges of a field, and they were baled wet and hot, so can’t be used for critters be it feed or bedding but they can be used for safe target practise and they can be used for safe garden bedding as long as we were masks when working with them cuz they will for sure have mold in them, or they will work at being set on their sides, end to end as a rapid and easy way to add in another four feet high by four feet wide instant garden bed for the coming year.
Just another Day on the Farm 
That is the only way I use them in the garden now. I made the mistake of using old hay for mulch and I’m still regretting it. The weeds and over invasive grasses was not worth it. Still digging them out to this day. I do like the idea of burying them.
I have used old hay in the gardens, I tend to use it more for bedding down the tree’s, bushes and for pathways, with the straw going on the beds but given that most of the time, you can’t even see my soil due to green cover, its not that much of a issue for me. i think it was two years ago, the really, really wet spring in our neck of the woods, no one could get any oats etc out into the fields and so there was no straw to be had, I was able to get just four large straw bales from the year before for my barn use, so everything that year got done into hay, I found the biggest issue for me at least, was that it heated up and composted so much faster then the straw does..
I can see if you keep a clean and tidy garden that old hay would need to be very, very thick or it would be a issue for sure.. how deep do you go on your bedding, I tend to do a min of six to eight inches and perfer a full ten to twelve for some things..
LUCKY!!
Very pleased yes, and I will need to try and give him something for his time and gas, as it will be a number of trips from that field to my place.