But your current mushrooms aren't exactly worthless. You can eat them (try each one and see the results...I can't remember which, but some of them do odd things), give them to villagers as "furniture", sell them at Re-Tail, use them to decorate your town or house...
I have an "Elf Ring" in my town: various mushrooms set in a ring around a tree stump with one of the patterns on it. It's next to my double hot springs!
I also have an area (I saw it called a mushroom farm) where I planted a grove of saplings and am trying to get every pattern there by cutting the trees with the silver axe when they are mature. If I get a duplicate, I dig it up and plant another sapling. I hope to get a lot of mushrooms there in November just for the fun of it (already have the whole mush series, plus extra pieces).
I did not think of these myself, btw. Either read about them or saw them in dream towns...
Have fun with your mushrooms!