Hi Marion
The easiest and much the best way to start is to wait and allow natural regeneration, whilst cutting and clearing the grass, or grazing, in the autumn, and early spring.
My meadow is on open invite for the next 2 weeks, so you might like to come over and have a look at what I have, which is a good mix of naturally regenerated flowers and some areas are already species rich. Depending on your ground conditions, it is likely that your natural seedbank will have many of the same plants. I'm 12 miles away.
If you will have cleared ground and bare earth patches this autumn, and you really can't wait for natural regeneration, or you already have some naturally regenerated plants and want to augment them, then you may find local North Devon, even North Molton, seed including yellow rattle, to introduce, if you try posting on the MM email exchange and the facebook page as well.
Personally, I find that divisions are more reliable than seed to start off with.
Bush vetch, meadow vetchling, foxgloves, and common valerian have ripe seeds in the hedgerows at the moment. The bees were mad for the bush vetch last month. There's lots of tufted vetch in flower on the B3227 so you could collect seed in a month's time. Last year, in August, I collected masses of greater birdsfoot trefoil seeds from laybys on that road, and yellow toadflax and many more from the hedgerows on the lanes around S Molton, in Sept. The wider roads have greater offerings than the narrow lanes which are usually cut back.
Alternatively contact Devon Wildlife Trust who sometimes sell dry seed or can sometimes arrange for some green hay. ENPA posted on the MM facebook page on 28 July that they harvested seed from a farm at Withypool.
I appreciate that you want Exmoor plants, ie
local seed.
For anyone else reading this I strongly suggest that you read the Moor Meadows and Plantlife Meadows Hub websites first. I didn't. I sowed before I became aware of and joined MM. I had a huge shock later, after reading David Crook's topic
viewtopic.php?f=23&t=55&p=62#p62 and also Steve Pollard's and Richard Lewis' posts here, to discover that my "gardening" frame of mind does not apply to fields. I'd made mistakes by buying and trying to introduce (to a good site already full of its own natural and local-variation-specific flowers,) commercially produced seed of plants I didn't already have, and which were not very immediately local even though they were from Devon and other South West suppliers. To a purist, I could have 'contaminated' my naturally rich seed bank. Luckily it failed! (
NB see last comment below)
(Update: Oh, great - having been thoroughly convinced as per the preceding para, and backed by one ecologist who visited - I have just received another ecologist's report recommending green hay - or - an Emorsgate mix curated following a soil analysis (so plants that can cope, but not necessarily of very local provenance). It's not so easy or straightforward, but I think personally, I will stick with natural regeneration. Perhaps I should dismount from my new hobby horse.)