If they are in decent shape, I would donate the magazines to the local public library. If they don't need them, they'll email their fellows, and ship them where they are needed. Used book stores may also be interested, and will pay a few pence each. Worst case, recycle them.
Where I work, the seeds from last year are donated to local schools, churches, and public gardens, so that may be a possibility for your seeds, as long as they have been kept cool and dry.

The magazines are as new

All the easier to sell them to a used book store, though you'll rarely get more than 1/4 of what you paid for them, and usually much less. If your budget is like mine, these days, every little bit helps.

Is the magazine still in circulation? Print publication is slowly going way of velociraptor. One major newspaper I've worked for years ago is almost entirely digital now. Nobody wants to read yesterday's news any more. Now you get it as it happens online. Think of all the resources that saves - the trees, gasoline, no inky fingers or stacks of old newspapers in the landfill.

I keep old magazines for 12 months in case I want to refer to them. Then I cut out any interesting articles for reference, and put them in the recycling bin

I totally agree with Bathgate. When it comes to large tasks I am a little bit at a time type of person so I suggest that you dispose of 5 magazines every week by a method of your choice. If there are any interesting articles, clip them out so to speak by taking digital photos of the articles and saving them in a file in your computer. By this method, you avoid bulky scrapbooks.

Advertise them on your local Freecycle group. My collection of Gardeners World magazines were taken by a newly formed gardening group a couple of years ago.

after lockdown offer them to your local garden group, they may be happy to take them. I have 20yrs worth of The Garden the RHS publication.

There is something very comforting in having a physical magazine especially to read in bed. Softer if you fall asleep on it rather than a hard edged laptop.

as for old seed if it is only a yr old it may be viable next yr. But I have put old seed [5yrs +] in with the bird mix and just let the birds have a varied diet.

I love a good read too but de-clutting feels great.

I'm with Shirley Tulip. Ive put gardening mags on Freecycle or Next Door and they are snapped up. It's good for new gardeners as it shows what to do each month. i also have put Which? mags on there and people love them.